sponge

• n.

• スポンジ、海綿質、海綿、海綿体

• adj.

• 海綿状の

関

cancellous、cavernous body、corpus cavernosum、Porifera、spongiform、spongiosa、spongy

　 　 　 　 　 　 　

WordNet

1. wipe with a sponge, so as to clean or moisten
2. a porous mass of interlacing fibers that forms the internal skeleton of various marine animals and usable to absorb water or any porous rubber or cellulose product similarly used
3. primitive multicellular marine animal whose porous body is supported by a fibrous skeletal framework; usually occurs in sessile colonies (同)poriferan, parazoan
4. erase with a sponge; as of words on a blackboard
5. gather sponges, in the ocean
6. soak up with a sponge
7. easily squashed; resembling a sponge in having soft porous texture and compressibility; "spongy bread" (同)squashy, squishy, spongelike
8. like a sponge in being able to absorb liquids and yield it back when compressed (同)spongelike
9. coextensive with the subkingdom Parazoa: sponges (同)phylum Porifera
10. a workman employed to collect sponges
11. clean with a sponge, by rubbing (同)sponge off

PrepTutorEJDIC

1. 〈C〉『海綿動物』 / 〈C〉〈U〉『海綿』,スポンジ;(一般に)海綿(スポンジ)状の物 / 〈C〉《比喩(ひゆ)的に》(海綿のように)何かをふんだんに吸収する人(物) / 〈C〉《話》いそうろう,食客 / 〈C〉〈U〉(外科手術用の)ガーゼ帯 / …‘を'海綿(スポンジ)で洗う(ぬらす,ふく) / 〈液体〉‘を'海綿(スポンジなど)で吸い取る《+『up』+『名,』+『名』+『up』》 / 《話》…‘を'せびり取る;…‘に'せびる / 〈海綿などが〉液体を吸収する / 《話》(人に)たかる《+『on』(『upon, off』)+『名』〈人〉》
2. 海綿状の多孔質の;吸収性の
3. 海綿採集人(船) / 《話》食客,いそうろう

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/07/08 16:44:56」(JST)

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This article is about the aquatic animal. For the porous cleaning tool, see Sponge (material). For other uses, see Sponge (disambiguation).

Sponge Temporal range: Ediacaran–Recent PreЄ Є O S D C P T J K Pg N
A stove-pipe sponge
Scientific classification
Kingdom:	Animalia
Phylum:	"Porifera" Grant in Todd, 1836
Classes
Calcarea Hexactinellida Demospongiae Homoscleromorpha

Sponges are animals of the phylum Porifera (/pɒˈrɪfərə/; meaning "pore bearer"). They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes.

Overview

Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues and organs, and have no body symmetry. The shapes of their bodies are adapted for maximal efficiency of water flow through the central cavity, where it deposits nutrients, and leaves through a hole called the osculum. Many sponges have internal skeletons of spongin and/or spicules of calcium carbonate or silica. All sponges are sessile aquatic animals. Although there are freshwater species, the great majority are marine (salt water) species, ranging from tidal zones to depths exceeding 8,800 m (5.5 mi).

While most of the approximately 5,000–10,000 known species feed on bacteria and other food particles in the water, some host photosynthesizing micro-organisms as endosymbionts and these alliances often produce more food and oxygen than they consume. A few species of sponge that live in food-poor environments have become carnivores that prey mainly on small crustaceans.

Most species use sexual reproduction, releasing sperm cells into the water to fertilize ova that in some species are released and in others are retained by the "mother". The fertilized eggs form larvae which swim off in search of places to settle. Sponges are known for regenerating from fragments that are broken off, although this only works if the fragments include the right types of cells. A few species reproduce by budding. When conditions deteriorate, for example as temperatures drop, many freshwater species and a few marine ones produce gemmules, "survival pods" of unspecialized cells that remain dormant until conditions improve and then either form completely new sponges or recolonize the skeletons of their parents.

The mesohyl functions as an endoskeleton in most sponges, and is the only skeleton in soft sponges that encrust hard surfaces such as rocks. More commonly, the mesohyl is stiffened by mineral spicules, by spongin fibers or both. Demosponges use spongin, and in many species, silica spicules and in some species, calcium carbonate exoskeletons. Demosponges constitute about 90% of all known sponge species, including all freshwater ones, and have the widest range of habitats. Calcareous sponges, which have calcium carbonate spicules and, in some species, calcium carbonate exoskeletons, are restricted to relatively shallow marine waters where production of calcium carbonate is easiest. The fragile glass sponges, with "scaffolding" of silica spicules, are restricted to polar regions and the ocean depths where predators are rare. Fossils of all of these types have been found in rocks dated from 580 million years ago. In addition Archaeocyathids, whose fossils are common in rocks from 530 to 490 million years ago, are now regarded as a type of sponge.

The sponge's closest single-celled relatives are thought to be choanoflagellates, which strongly resemble the cells sponges use to drive their water flow systems and capture most of their food. Sponges are generally agreed, also, to not form a monophyletic group, in other words do not include all and only the descendants of a common ancestor, because Eumetazoa (more complex animals) are thought to be descendants of a subgroup of sponges. However it is uncertain which group of sponges is closest to Eumetazoa, as both calcareous sponges and a subgroup of demosponges called Homoscleromorpha have been nominated by different researchers. In addition, a study in 2008 suggested the earliest animals may have been similar to modern comb jellies.

The few species of demosponge that have entirely soft fibrous skeletons with no hard elements have been used by humans over thousands of years for several purposes, including as padding and as cleaning tools. By the 1950s, though, these had been overfished so heavily that the industry almost collapsed, and most sponge-like materials are now synthetic. Sponges and their microscopic endosymbionts are now being researched as possible sources of medicines for treating a wide range of diseases. Dolphins have been observed using sponges as tools while foraging.

Distinguishing features

Further information: Cnidaria and Ctenophore

Sponges constitute the phylum Porifera, and have been defined as sessile metazoans (multicelled immobile animals) that have water intake and outlet openings connected by chambers lined with choanocytes, cells with whip-like flagella. However, a few carnivorous sponges have lost these water flow systems and the choanocytes. All known living sponges can remold their bodies, as most types of their cells can move within their bodies and a few can change from one type to another.

Like cnidarians (jellyfish, etc.) and ctenophores (comb jellies), and unlike all other known metazoans, sponges' bodies consist of a non-living jelly-like mass sandwiched between two main layers of cells. Cnidarians and ctenophores have simple nervous systems, and their cell layers are bound by internal connections and by being mounted on a basement membrane (thin fibrous mat, also known as "basal lamina"). Sponges have no nervous systems, their middle jelly-like layers have large and varied populations of cells, and some types of cells in their outer layers may move into the middle layer and change their functions.

	Sponges	Cnidarians and ctenophores
Nervous system	No	Yes, simple
Cells in each layer bound together	No, except that Homoscleromorpha have basement membranes.	Yes: inter-cell connections; basement membranes
Number of cells in middle "jelly" layer	Many	Few
Cells in outer layers can move inwards and change functions	Yes	No

Basic structure

Cell types

    Mesohyl

    Pinacocyte

    Choanocyte

    Lophocyte

    Porocyte

    Oocyte

    Archeocyte

    Sclerocyte

    Spicule

    Water flow

Main cell types of Porifera

A sponge's body is hollow and is held in shape by the mesohyl, a jelly-like substance made mainly of collagen and reinforced by a dense network of fibers also made of collagen. The inner surface is covered with choanocytes, cells with cylindrical or conical collars surrounding one flagellum per choanocyte. The wave-like motion of the whip-like flagella drives water through the sponge's body. All sponges have ostia, channels leading to the interior through the mesohyl, and in most sponges these are controlled by tube-like porocytes that form closable inlet valves. Pinacocytes, plate-like cells, form a single-layered external skin over all other parts of the mesohyl that are not covered by choanocytes, and the pinacocytes also digest food particles that are too large to enter the ostia, while those at the base of the animal are responsible for anchoring it.

Other types of cell live and move within the mesohyl:

• Lophocytes are amoeba-like cells that move slowly through the mesohyl and secrete collagen fibres.
• Collencytes are another type of collagen-producing cell.
• Rhabdiferous cells secrete polysaccharides that also form part of the mesohyl.
• Oocytes and spermatocytes are reproductive cells.
• Sclerocytes secrete the mineralized spicules ("little spines") that form the skeletons of many sponges and in some species provide some defense against predators.
• In addition to or instead of sclerocytes, demosponges have spongocytes that secrete a form of collagen that polymerizes into spongin, a thick fibrous material that stiffens the mesohyl.
• Myocytes ("muscle cells") conduct signals and cause parts of the animal to contract.
• "Grey cells" act as sponges' equivalent of an immune system.
• Archaeocytes (or amoebocytes) are amoeba-like cells that are totipotent, in other words each is capable of transformation into any other type of cell. They also have important roles in feeding and in clearing debris that block the ostia.

Glass sponges' syncytia

    Water flow

    Main syncitium

    Spicules

    Choanosyncitium

    and collar bodies

    showing interior

The glass sponge Euplectella

Glass sponges present a distinctive variation on this basic plan. Their spicules, which are made of silica, form a scaffolding-like framework between whose rods the living tissue is suspended like a cobweb that contains most of the cell types. This tissue is a syncytium that in some ways behaves like many cells that share a single external membrane, and in others like a single cell with multiple nuclei. The mesohyl is absent or minimal. The syncytium's cytoplasm, the soupy fluid that fills the interiors of cells, is organized into "rivers" that transport nuclei, organelles ("organs" within cells) and other substances. Instead of choanocytes, they have further syncytia, known as choanosyncytia, which form bell-shaped chambers where water enters via perforations. The insides of these chambers are lined with "collar bodies", each consisting of a collar and flagellum but without a nucleus of its own. The motion of the flagella sucks water through passages in the "cobweb" and expels it via the open ends of the bell-shaped chambers.

Some types of cells have a single nucleus and membrane each, but are connected to other single-nucleus cells and to the main syncytium by "bridges" made of cytoplasm. The sclerocytes that build spicules have multiple nuclei, and in glass sponge larvae they are connected to other tissues by cytoplasm bridges; such connections between sclerocytes have not so far been found in adults, but this may simply reflect the difficulty of investigating such small-scale features. The bridges are controlled by "plugged junctions" that apparently permit some substances to pass while blocking others.

Water flow and body structures

Asconoid

Syconoid

Leuconoid

    Pinacocytes

    Choanocytes

    Mesohyl

    Water flow

Porifera body structures

Most sponges work rather like chimneys: they take in water at the bottom and eject it from the osculum ("little mouth") at the top. Since ambient currents are faster at the top, the suction effect that they produce does some of the work for free. Sponges can control the water flow by various combinations of wholly or partially closing the osculum and ostia (the intake pores) and varying the beat of the flagella, and may shut it down if there is a lot of sand or silt in the water.

Although the layers of pinacocytes and choanocytes resemble the epithelia of more complex animals, they are not bound tightly by cell-to-cell connections or a basal lamina (thin fibrous sheet underneath). The flexibility of these layers and re-modeling of the mesohyl by lophocytes allow the animals to adjust their shapes throughout their lives to take maximum advantage of local water currents.

The simplest body structure in sponges is a tube or vase shape known as "asconoid", but this severely limits the size of the animal. The body structure is characterized by a stalk-like spongocoel surrounded by a single layer of choanocytes. If it is simply scaled up, the ratio of its volume to surface area increases, because surface increases as the square of length or width while volume increases proportionally to the cube. The amount of tissue that needs food and oxygen is determined by the volume, but the pumping capacity that supplies food and oxygen depends on the area covered by choanocytes. Asconoid sponges seldom exceed 1 mm (0.039 in) in diameter.

Diagram of a syconoid sponge.

Some sponges overcome this limitation by adopting the "syconoid" structure, in which the body wall is pleated. The inner pockets of the pleats are lined with choanocytes, which connect to the outer pockets of the pleats by ostia. This increase in the number of choanocytes and hence in pumping capacity enables syconoid sponges to grow up to a few centimeters in diameter.

The "leuconoid" pattern boosts pumping capacity further by filling the interior almost completely with mesohyl that contains a network of chambers lined with choanocytes and connected to each other and to the water intakes and outlet by tubes. Leuconid sponges grow to over 1 m (3.3 ft) in diameter, and the fact that growth in any direction increases the number of choanocyte chambers enables them to take a wider range of forms, for example "encrusting" sponges whose shapes follow those of the surfaces to which they attach. All freshwater and most shallow-water marine sponges have leuconid bodies. The networks of water passages in glass sponges are similar to the leuconid structure. In all three types of structure the cross-section area of the choanocyte-lined regions is much greater than that of the intake and outlet channels. This makes the flow slower near the choanocytes and thus makes it easier for them to trap food particles. For example in Leuconia, a small leuconoid sponge about 10 centimetres (3.9 in) tall and 1 centimetre (0.39 in) in diameter, water enters each of more than 80,000 intake canals at 6 cm per minute. However, because Leuconia has more than 2 million flagellated chambers whose combined diameter is much greater than that of the canals, water flow through chambers slows to 3.6 cm per hour, making it easy for choanocytes to capture food. All the water is expelled through a single osculum at about 8.5 cm per second, fast enough to carry waste products some distance away.

    Pinacocyte

    Choanocyte

    Archeocytes and other cells in
    mesohyl

    Mesohyl

    Spicules

    Calcium carbonate

    Seabed / rock

    Water flow

Sponge with calcium carbonate skeleton

Skeleton

In zoology a skeleton is any fairly rigid structure of an animal, irrespective of whether it has joints and irrespective of whether it is biomineralized. The mesohyl functions as an endoskeleton in most sponges, and is the only skeleton in soft sponges that encrust hard surfaces such as rocks. More commonly the mesohyl is stiffened by mineral spicules, by spongin fibers or both. Spicules may be made of silica or calcium carbonate, and vary in shape from simple rods to three-dimensional "stars" with up to six rays. Spicules are produced by sclerocyte cells, and may be separate, connected by joints, or fused.

Some sponges also secrete exoskeletons that lie completely outside their organic components. For example sclerosponges ("hard sponges") have massive calcium carbonate exoskeletons over which the organic matter forms a thin layer with choanocyte chambers in pits in the mineral. These exoskeletons are secreted by the pinacocytes that form the animals' skins.

Classes

Sponges were traditionally distributed in three classes: calcareous sponges (Calcarea), glass sponges (Hexactinellida) and demosponges (Demospongiae). However, studies have shown that the Homoscleromorpha, a group thought to belong to the Demospongiae, is actually phylogenetically well separated. Therefore, they have recently been recognized as the fourth class of sponges.

Sponges are divided into classes mainly according to the composition of their skeletons:

	Type of cells	Spicules	Spongin fibers	Massive exoskeleton	Body form
Calcarea	Single nucleus, single external membrane	Calcite May be individual or large masses	Never	Common. Made of calcite if present.	Asconoid, syconoid, leuconoid or solenoid
Hexactinellidas	Mostly syncytia in all species	Silica May be individual or fused	Never	Never	Leuconoid
Demospongiae	Single nucleus, single external membrane	Silica	In many species	In some species. Made of aragonite if present.	Leuconoid
Homoscleromorpha	Single nucleus, single external membrane	Silica	In many species	Never	Sylleibid or leuconoid

Vital functions

Spongia officinalis, "the kitchen sponge", is dark grey when alive

Movement

Although adult sponges are fundamentally sessile animals, some marine and freshwater species can move across the sea bed at speeds of 1–4 mm (0.039–0.157 in) per day, as a result of amoeba-like movements of pinacocytes and other cells. A few species can contract their whole bodies, and many can close their oscula and ostia. Juveniles drift or swim freely, while adults are stationary.

Respiration, feeding and excretion

Sponges do not have distinct circulatory, respiratory, digestive, and excretory systems – instead the water flow system supports all these functions. They filter food particles out of the water flowing through them. Particles larger than 50 micrometers cannot enter the ostia and pinacocytes consume them by phagocytosis (engulfing and internal digestion). Particles from 0.5 μm to 50 μm are trapped in the ostia, which taper from the outer to inner ends. These particles are consumed by pinacocytes or by archaeocytes which partially extrude themselves through the walls of the ostia. Bacteria-sized particles, below 0.5 micrometers, pass through the ostia and are caught and consumed by choanocytes. Since the smallest particles are by far the most common, choanocytes typically capture 80% of a sponge's food supply. Archaeocytes transport food packaged in vesicles from cells that directly digest food to those that do not. At least one species of sponge has internal fibers that function as tracks for use by nutrient-carrying archaeocytes, and these tracks also move inert objects.

It used to be claimed that glass sponges could live on nutrients dissolved in sea water and were very averse to silt. However a study in 2007 found no evidence of this and concluded that they extract bacteria and other micro-organisms from water very efficiently (about 79%) and process suspended sediment grains to extract such prey. Collar bodies digest food and distribute it wrapped in vesicles that are transported by dynein "motor" molecules along bundles of microtubules that run throughout the syncytium.

Sponges' cells absorb oxygen by diffusion from water into cells as water flows through body, into which carbon dioxide and other soluble waste products such as ammonia also diffuse. Archeocytes remove mineral particles that threaten to block the ostia, transport them through the mesohyl and generally dump them into the outgoing water current, although some species incorporate them into their skeletons.

Carnivorous sponges

A few species that live in waters where the supply of food particles is very poor prey on crustaceans and other small animals. Most belong to the family Cladorhizidae, but a few members of the Guitarridae and Esperiopsidae are also carnivores. In most cases little is known about how they actually capture prey, although some species are thought to use either sticky threads or hooked spicules. Most carnivorous sponges live in deep waters, up to 8,840 m (5.49 mi), and the development of deep-ocean exploration techniques is expected to lead to the discovery of several more. However one species has been found in Mediterranean caves at depths of 17–23 m (56–75 ft), alongside the more usual filter feeding sponges. The cave-dwelling predators capture crustaceans under 1 mm (0.039 in) long by entangling them with fine threads, digest them by enveloping them with further threads over the course of a few days, and then return to their normal shape; there is no evidence that they use venom.

Most known carnivorous sponges have completely lost the water flow system and choanocytes. However the genus Chondrocladia uses a highly modified water flow system to inflate balloon-like structures that are used for capturing prey.

Endosymbionts

Freshwater sponges often host green algae as endosymbionts within archaeocytes and other cells, and benefit from nutrients produced by the algae. Many marine species host other photosynthesizing organisms, most commonly cyanobacteria but in some cases dinoflagellates. Symbiotic cyanobacteria may form a third of the total mass of living tissue in some sponges, and some sponges gain 48% to 80% of their energy supply from these micro-organisms. In 2008 a University of Stuttgart team reported that spicules made of silica conduct light into the mesohyl, where the photosynthesizing endosymbionts live. Sponges that host photosynthesizing organisms are most common in waters with relatively poor supplies of food particles, and often have leafy shapes that maximize the amount of sunlight they collect.

A recently discovered carnivorous sponge that lives near hydrothermal vents hosts methane-eating bacteria, and digests some of them.

"Immune" system

Sponges do not have the complex immune systems of most other animals. However they reject grafts from other species but accept them from other members of their own species. In a few marine species, gray cells play the leading role in rejection of foreign material. When invaded, they produce a chemical that stops movement of other cells in the affected area, thus preventing the intruder from using the sponge's internal transport systems. If the intrusion persists, the grey cells concentrate in the area and release toxins that kill all cells in the area. The "immune" system can stay in this activated state for up to three weeks.

Reproduction

Asexual

The freshwater sponge Spongilla lacustris

Sponges have three asexual methods of reproduction: after fragmentation; by budding; and by producing gemmules. Fragments of sponges may be detached by currents or waves. They use the mobility of their pinacocytes and choanocytes and reshaping of the mesohyl to re-attach themselves to a suitable surface and then rebuild themselves as small but functional sponges over the course of several days. The same capabilities enable sponges that have been squeezed through a fine cloth to regenerate. A sponge fragment can only regenerate if it contains both collencytes to produce mesohyl and archeocytes to produce all the other cell types. A very few species reproduce by budding.

Gemmules are "survival pods" which a few marine sponges and many freshwater species produce by the thousands when dying and which some, mainly freshwater species, regularly produce in autumn. Spongocytes make gemmules by wrapping shells of spongin, often reinforced with spicules, round clusters of archeocytes that are full of nutrients. Freshwater gemmules may also include phytosynthesizing symbionts. The gemmules then become dormant, and in this state can survive cold, drying out, lack of oxygen and extreme variations in salinity. Freshwater gemmules often do not revive until the temperature drops, stays cold for a few months and then reaches a near-"normal" level. When a gemmule germinates, the archeocytes round the outside of the cluster transform into pinacocytes, a membrane over a pore in the shell bursts, the cluster of cells slowly emerges, and most of the remaining archeocytes transform into other cell types needed to make a functioning sponge. Gemmules from the same species but different individuals can join forces to form one sponge. Some gemmules are retained within the parent sponge, and in spring it can be difficult to tell whether an old sponge has revived or been "recolonized" by its own gemmules.

Sexual

Most sponges are hermaphrodites (function as both sexes simultaneously), although sponges have no gonads (reproductive organs). Sperm are produced by choanocytes or entire choanocyte chambers that sink into the mesohyl and form spermatic cysts while eggs are formed by transformation of archeocytes, or of choanocytes in some species. Each egg generally acquires a yolk by consuming "nurse cells". During spawning, sperm burst out of their cysts and are expelled via the osculum. If they contact another sponge of the same species, the water flow carries them to choanocytes that engulf them but, instead of digesting them, metamorphose to an ameboid form and carry the sperm through the mesohyl to eggs, which in most cases engulf the carrier and its cargo.

A few species release fertilized eggs into the water, but most retain the eggs until they hatch. There are four types of larvae, but all are balls of cells with an outer layer of cells whose flagellae or cilia enable the larvae to move. After swimming for a few days the larvae sink and crawl until they find a place to settle. Most of the cells transform into archeocytes and then into the types appropriate for their locations in a miniature adult sponge.

Glass sponge embryos start by dividing into separate cells, but once 32 cells have formed they rapidly transform into larvae that externally are ovoid with a band of cilia round the middle that they use for movement, but internally have the typical glass sponge structure of spicules with a cobweb-like main syncitium draped around and between them and choanosyncytia with multiple collar bodies in the center. The larvae then leave their parents' bodies.

Life cycle

Sponges in temperate regions live for at most a few years, but some tropical species and perhaps some deep-ocean ones may live for 200 years or more. Some calcified demosponges grow by only 0.2 mm (0.0079 in) per year and, if that rate is constant, specimens 1 m (3.3 ft) wide must be about 5,000 years old. Some sponges start sexual reproduction when only a few weeks old, while others wait until they are several years old.

Coordination of activities

Adult sponges lack neurons or any other kind of nervous tissue. However most species have the ability to perform movements that are coordinated all over their bodies, mainly contractions of the pinacocytes, squeezing the water channels and thus expelling excess sediment and other substances that may cause blockages. Some species can contract the osculum independently of the rest of the body. Sponges may also contract in order to reduce the area that is vulnerable to attack by predators. In cases where two sponges are fused, for example if there is a large but still unseparated bud, these contraction waves slowly become coordinated in both of the "Siamese twins". The coordinating mechanism is unknown, but may involve chemicals similar to neurotransmitters. However glass sponges rapidly transmit electrical impulses through all parts of the syncytium, and use this to halt the motion of their flagella if the incoming water contains toxins or excessive sediment. Myocytes are thought to be responsible for closing the osculum and for transmitting signals between different parts of the body.

Sponges contain genes very similar to those that contain the "recipe" for the post-synaptic density, an important signal-receiving structure in the neurons of all other animals. However in sponges these genes are only activated in "flask cells" that appear only in larvae and may provide some sensory capability while the larvae are swimming. This raises questions about whether flask cells represent the predecessors of true neurons or are evidence that sponges' ancestors had true neurons but lost them as they adapted to a sessile lifestyle.

Ecology

Euplectella aspergillum is a deep ocean glass sponge; seen here at a depth of 2,572 metres (8,438 ft) off the coast of California.

Habitats

Sponges are worldwide in their distribution, from the polar regions to the tropics. Most live in quiet, clear waters, because sediment stirred up by waves or currents would block their pores, making it difficult for them to feed and breathe. The greatest numbers of sponges are usually found on firm surfaces such as rocks, but some sponges can attach themselves to soft sediment by means of a root-like base.

Sponges are more abundant but less diverse in temperate waters than in tropical waters, possibly because organisms that prey on sponges are more abundant in tropical waters. Glass sponges are the most common in polar waters and in the depths of temperate and tropical seas, as their very porous construction enables them to extract food from these resource-poor waters with the minimum of effort. Demosponges and calcareous sponges are abundant and diverse in shallower non-polar waters.

The different classes of sponge live in different ranges of habitat:

	Water type	Depth	Type of surface
Calcarea	Marine	less than 100 m (330 ft)	Hard
Glass sponges	Marine	Deep	Soft or firm sediment
Demosponges	Marine, brackish; and about 150 freshwater species	Inter-tidal to abyssal; a carnivorous demosponge has been found at 8,840 m (5.49 mi)	Any

As primary producers

Sponges with photosynthesizing endosymbionts produce up to three times more oxygen than they consume, as well as more organic matter than they consume. Such contributions to their habitats' resources are significant along Australia's Great Barrier Reef but relatively minor in the Caribbean.

Defenses

Holes made by clionaid sponge (producing the trace Entobia) after the death of a modern bivalve shell of species Mercenaria mercenaria, from North Carolina

Close-up of the sponge boring Entobia in a modern oyster valve. Note the chambers which are connected by short tunnels.

Many sponges shed Sponge spicules, forming a dense carpet several meters deep that keeps away echinoderms which would otherwise prey on the sponges. They also produce toxins that prevent other sessile organisms such as bryozoans or sea squirts from growing on or near them, making sponges very effective competitors for living space. One of many examples includes ageliferin.

A few species, such as the Caribbean fire sponge Tedania ignis, cause a severe rash in humans who handle them. Turtles and some fish feed mainly on sponges. It is often said that sponges produce chemical defenses against such predators. However an experiment showed that there is no relationship between the toxicity of chemicals produced by sponges and how they taste to fish, which would diminish the usefulness of chemical defenses as deterrents. Predation by fish may even help to spread sponges by detaching fragments.

Glass sponges produce no toxic chemicals, and live in very deep water where predators are rare.

Predation

Sponge flies, also known as spongilla-flies (Neuroptera, Sisyridae), are specialist predators of freshwater sponges. The female lays her eggs on vegetation overhanging water. The larvae hatch and drop into the water where they seek out sponges to feed on. They use their elongated mouthparts to pierce the sponge and suck the fluids within. The larvae of some species cling to the surface of the sponge while others take refuge in the sponge's internal cavities. The fully grown larvae leave the water and spin a cocoon in which to pupate.

Bioerosion

The Caribbean chicken-liver sponge Chondrilla nucula secretes toxins that kill coral polyps, allowing the sponges to grow over the coral skeletons. Others, especially in the family Clionaidae, use corrosive substances secreted by their archeocytes to tunnel into rocks, corals and the shells of dead mollusks. Sponges may remove up to 1 m (3.3 ft) per year from reefs, creating visible notches just below low-tide level.

Diseases

Caribbean sponges of the genus Aplysina suffer from Aplysina red band syndrome. This causes Aplysina to develop one or more rust-colored bands, sometimes with adjacent bands of necrotic tissue. These lesions may completely encircle branches of the sponge. The disease appears to be contagious and impacts approximately 10 percent of A. cauliformis on Bahamian reefs. The rust-colored bands are caused by a cyanobacterium, but it is unknown whether this organism actually causes the disease.

Collaboration with other organisms

In addition to hosting photosynthesizing endosymbionts, sponges are noted for their wide range of collaborations with other organisms. The relatively large encrusting sponge Lissodendoryx colombiensis is most common on rocky surfaces, but has extended its range into seagrass meadows by letting itself be surrounded or overgrown by seagrass sponges, which are distasteful to the local starfish and therefore protect Lissodendoryx against them; in return the seagrass sponges get higher positions away from the sea-floor sediment.

Shrimps of the genus Synalpheus form colonies in sponges, and each shrimp species inhabits a different sponge species, making Synalpheus one of the most diverse crustacean genera. Specifically, Synalpheus regalis utilizes the sponge not only as a food source, but also as a defense against other shrimp and predators. As many as 16,000 individuals inhabit a single loggerhead sponge, feeding off the larger particles that collect on the sponge as it filters the ocean to feed itself.

Evolutionary history

Fossil record

 

Fossil sponge Raphidonema faringdonense from Cretaceous rocks in England

1

2

3

4

5

6

7

1: Gap  2: Central cavity  3 Internal wall  4: Pore (all walls have pores)  5 Septum  6 Outer wall  7 Holdfast

Archaeocyathid structure

24-isopropylcholestane is a stable derivative of 24-isopropylcholesterol, which is said to be produced by demosponges but not by eumetazoans ("true animals", i.e. cnidarians and bilaterians). Since choanoflagellates are thought to be animals' closest single-celled relatives, a team of scientists examined the biochemistry and genes of one choanoflagellate species. They concluded that this species could not produce 24-isopropylcholesterol but that investigation of a wider range of choanoflagellates would be necessary in order to prove that the fossil 24-isopropylcholestane could only have been produced by demosponges. Although a previous publication reported traces of the chemical 24-isopropylcholestane in ancient rocks dating to 1,800 million years ago, recent research using a much more accurately dated rock series has revealed that these biomarkers only appear before the end of the Marinoan glaciation approximately 635 million years ago, and that "Biomarker analysis has yet to reveal any convincing evidence for ancient sponges pre-dating the first globally extensive Neoproterozoic glacial episode (the Sturtian, ~713 million years ago in Oman)". Nevertheless, this 'sponge biomarker' could have other sources - such as marine algae — so may not constrain the origin of Porifera.

Although molecular clocks and biomarkers suggest sponges existed well before the Cambrian explosion of life, silica spicules like those of demosponges are absent from the fossil record until the Cambrian, although one unsubstantiated report exists of spicules in rocks dated around 750 million years ago, although this appears unlikely based on the above reference. Well-preserved fossil sponges from about 580 million years ago in the Ediacaran period have been found in the Doushantuo Formation. These fossils, which include spicules, pinacocytes, porocytes, archeocytes, sclerocytes and the internal cavity, have been classified as demosponges. Fossils of glass sponges have been found from around 540 million years ago in rocks in Australia, China and Mongolia. Early Cambrian sponges from Mexico belonging to the genus Kiwetinokia show evidence of fusion of several smaller spicules to form a single large spicule. Calcium carbonate spicules of calcareous sponges have been found in Early Cambrian rocks from about 530 to 523 million years ago in Australia. Other probable demosponges have been found in the Early Cambrian Chengjiang fauna, from 525 to 520 million years ago. Freshwater sponges appear to be much younger, as the earliest known fossils date from the Mid-Eocene period about 48 to 40 million years ago. Although about 90% of modern sponges are demosponges, fossilized remains of this type are less common than those of other types because their skeletons are composed of relatively soft spongin that does not fossilize well.

Archaeocyathids, which some classify as a type of coralline sponge, are common in the Cambrian period from about 530 million years ago, but apparently died out by the end of the Cambrian 490 million years ago.

Family tree

A choanoflagellate

Fungi Choanoflagellates Metazoa Glass sponges Demosponges Calcareous sponges Eumetazoa   Comb jellies Placozoa Cnidaria (jellyfish, etc.) Simplified family tree showing calcareous sponges as closest to more complex animals

Plants Fungi Metazoa Most demosponges Calcareous sponges Homoscleromorpha Eumetazoa Cnidaria (jellyfish, etc.) Other metazoans Simplified family tree showing Homoscleromorpha as closest to more complex animals

In the 1990s sponges were widely regarded as a monophyletic group, in other words all of them descended from a common ancestor that was itself a sponge, and as the "sister-group" to all other metazoans (multi-celled animals), which themselves form a monophyletic group. On the other hand some 1990s analyses also revived the idea that animals' nearest evolutionary relatives are choanoflagellates, single-celled organisms very similar to sponges' choanocytes – which would imply that most Metazoa evolved from very sponge-like ancestors and therefore that sponges may not be monophyletic, as the same sponge-like ancestors may have given rise both to modern sponges and to non-sponge members of Metazoa.

Analyses since 2001 have concluded that Eumetazoa (more complex than sponges) are more closely related to particular groups of sponges than to the rest of the sponges. Such conclusions imply that sponges are not monophyletic, because the last common ancestor of all sponges would also be a direct ancestor of the Eumetazoa, which are not sponges. A study in 2001 based on comparisons of ribosome DNA concluded that the most fundamental division within sponges was between glass sponges and the rest, and that Eumetazoa are more closely related to Calcareous sponges, those with calcium carbonate spicules, than to other types of sponge. In 2007 one analysis based on comparisons of RNA and another based mainly on comparison of spicules concluded that demosponges and glass sponges are more closely related to each other than either is to calcareous sponges, which in turn are more closely related to Eumetazoa.

Other anatomical and biochemical evidence links the Eumetazoa with Homoscleromorpha, a sub-group of demosponges. A comparison in 2007 of nuclear DNA, excluding glass sponges and comb jellies, concluded that: Homoscleromorpha are most closely related to Eumetazoa; calcareous sponges are the next closest; the other demosponges are evolutionary "aunts" of these groups; and the chancelloriids, bag-like animals whose fossils are found in Cambrian rocks, may be sponges. The sperm of Homoscleromorpha share with those of Eumetazoa features that those of other sponges lack. In both Homoscleromorpha and Eumetazoa layers of cells are bound together by attachment to a carpet-like basal membrane composed mainly of "type IV" collagen, a form of collagen not found in other sponges – although the spongin fibers that reinforce the mesohyl of all demosponges is similar to "type IV" collagen.

A comb jelly

The analyses described above concluded that sponges are closest to the ancestors of all Metazoa, in other words of all multi-celled animals including both sponges and more complex groups. However, another comparison in 2008 of 150 genes in each of 21 genera, ranging from fungi to humans but including only two species of sponge, suggested that comb jellies (ctenophora) are the most basal lineage of the Metazoa included in the sample. If this is correct, either modern comb jellies developed their complex structures independently of other Metazoa, or sponges' ancestors were more complex and all known sponges are drastically simplified forms. The study recommended further analyses using a wider range of sponges and other simple Metazoa such as Placozoa. The results of such an analysis, published in 2009, suggest that a return to the previous view may be warranted. 'Family trees' constructed using a combination of all available data – morphological, developmental and molecular – concluded that the sponges are in fact a monophyletic group, and with the cnidarians form the sister group to the bilaterians.

Archaeocyathids are very common fossils in rocks from the Early Cambrian about 530 to 520 million years ago but are not found after the Late Cambrian. It has been suggested that they were produced by: sponges; cnidarians; algae; foraminiferans; a completely separate phylum of animals, Archaeocyatha; or even a completely separate kingdom of life, labeled Archaeata or Inferibionta. Since the 1990s archaeocyathids have been regarded as a distinctive group of sponges.

= skin

= aragonite

= flesh

Halkieriid sclerite structure

It is difficult to fit chancelloriids into classifications of sponges or more complex animals. An analysis in 1996 concluded that they were closely related to sponges on the grounds that the detailed structure of chancellorid sclerites ("armor plates") is similar to that of fibers of spongin, a collagen protein, in modern keratose (horny) demosponges such as Darwinella. However another analysis in 2002 concluded that chancelloriids are not sponges and may be intermediate between sponges and more complex animals, among other reasons because their skins were thicker and more tightly connected than those of sponges. In 2008 a detailed analysis of chancelloriids' sclerites concluded that they were very similar to those of halkieriids, mobile bilaterian animals that looked like slugs in chain mail and whose fossils are found in rocks from the very Early Cambrian to the Mid Cambrian. If this is correct, it would create a dilemma, as it is extremely unlikely that totally unrelated organisms could have developed such similar sclerites independently, but the huge difference in the structures of their bodies makes it hard to see how they could be closely related.

Taxonomy

Levels in the Linnean taxonomy.

Linnaeus, who classified most kinds of sessile animals as belonging to the order Zoophyta in the class Vermes, mistakenly identified the genus Spongia as plants in the order Algae. For a long time thereafter sponges were assigned to a separate subkingdom, Parazoa ("beside the animals"), separate from the Eumetazoa which formed the rest of the kingdom Animalia. They are now classified as a paraphyletic phylum, from which the higher animals have evolved.

The phylum Porifera is further divided into classes mainly according to the composition of their skeletons:

• Hexactinellida (glass sponges) have silicate spicules, the largest of which have six rays and may be individual or fused. The main components of their bodies are syncytia in which large numbers of cell share a single external membrane.
• Calcarea have skeletons made of calcite, a form of calcium carbonate, which may form separate spicules or large masses. All the cells have a single nucleus and membrane.
• Most Demospongiae have silicate spicules or spongin fibers or both within their soft tissues. However a few also have massive external skeletons made of aragonite, another form of calcium carbonate. All the cells have a single nucleus and membrane.
• Archeocyatha are known only as fossils from the Cambrian period.

In the 1970s sponges with massive calcium carbonate skeletons were assigned to a separate class, Sclerospongiae, otherwise known as "coralline sponges". However in the 1980s it was found that these were all members of either the Calcarea or the Demospongiae.

So far scientific publications have identified about 9,000 poriferan species, of which: about 400 are glass sponges; about 500 are calcareous species; and the rest are demosponges. However some types of habitat, such as vertical rock and cave walls and galleries in rock and coral boulders, have been investigated very little, even in shallow seas.

Use

By dolphins

A report in 1997 described use of sponges as a tool by bottlenose dolphins in Shark Bay in Western Australia. A dolphin will attach a marine sponge to its rostrum, which is presumably then used to protect it when searching for food in the sandy sea bottom. The behavior, known as sponging, has only been observed in this bay, and is almost exclusively shown by females. A study in 2005 concluded that mothers teach the behavior to their daughters, and that all the sponge-users are closely related, suggesting that it is a fairly recent innovation.

By humans

Display of natural sponges for sale on Kalymnos in Greece

Main article: Sea sponge aquaculture

Skeleton

Main article: Sponge (material)

The calcium carbonate or silica spicules of most sponge genera make them too rough for most uses, but two genera, Hippospongia and Spongia, have soft, entirely fibrous skeletons. Early Europeans used soft sponges for many purposes, including padding for helmets, portable drinking utensils and municipal water filters. Until the invention of synthetic sponges, they were used as cleaning tools, applicators for paints and ceramic glazes and discreet contraceptives. However by the mid-20th century, over-fishing brought both the animals and the industry close to extinction. See also sponge diving.

Many objects with sponge-like textures are now made of substances not derived from poriferans. Synthetic sponges include personal and household cleaning tools, breast implants, and contraceptive sponges. Typical materials used are cellulose foam, polyurethane foam, and less frequently, silicone foam.

The luffa "sponge", also spelled loofah, which is commonly sold for use in the kitchen or the shower, is not derived from an animal but mainly from the fibrous "skeleton" of the sponge gourd (Luffa aegyptiaca, Cucurbitaceae).

Antibiotic compounds

Sponges have medicinal potential due to the presence in sponges themselves or their microbial symbionts of chemicals that may be used to control viruses, bacteria, tumors and fungi.

Other biologically active compounds

Main article: Sponge isolates

Halichondria produces the eribulin precursor halichondrin B

Lacking any protective shell or means of escape, sponges have evolved to synthesize a variety of unusual compounds. One such class is the oxidized fatty acid derivatives called oxylipins. Members of this family have been found to have anti-cancer, anti-bacterial and anti-fungal properties. One example isolated from the Okinawan plakortis sponges, plakoridine A, has shown potential as a cytotoxin to murine lymphoma cells.

See also

• Sponge reef
• Sponge Reef Project

References

Further reading

• Bergquist, Patricia R. (1978). Sponges. London: Hutchinson. ISBN 0-09-131820-3. .
• Hickman, C., Jr.; Roberts, L. & Larson, A. (2003). Animal Diversity (3rd ed.). New York: McGraw-Hill. ISBN 0-07-234903-4. .

External links

• Water flow and feeding in the phylum Porifera (sponges) – Flash animations of sponge body structures, water flow and feeding
• Bioerosion website at The College of Wooster
• Carsten's Spongepage, Information on the ecology and the biotechnological potential of sponges and their associated bacteria.
• History of Tarpon Springs, Florida sponge industry
• Nature's 'fibre optics' experts
• The Sponge Reef Project
• Queensland Museum information about sponges
• Queensland Museum Sessile marine invertebrates collections
• Queensland Museum Sessile marine invertebrates research
• Sponge Guide for Britain and Ireland, Bernard Picton, Christine Morrow & Rob van Soest
• World Porifera database, the world list of extant sponges, includes a searchable database.

UpToDate Contents

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• 1. 避妊の概要 overview of contraception
• 2. 海綿腎 medullary sponge kidney
• 3. 手術時のスポンジおよびその他の異物遺残：予防およびマネージメント retained surgical sponge gossypiboma and other retained surgical items prevention and management
• 4. 腎石灰沈着症 nephrocalcinosis
• 5. 成人におけるカルシウム結石の危険因子 risk factors for calcium stones in adults

English Journal

• Mechanically fractionated flour isolated from green bananas (M. cavendishii var. nanica) as a tool to increase the dietary fiber and phytochemical bioactivity of layer and sponge cakes.

• Segundo C1, Román L2, Gómez M2, Martínez MM3.
• Food chemistry.Food Chem.2017 Mar 15;219:240-248. doi: 10.1016/j.foodchem.2016.09.143. Epub 2016 Sep 22.
• This article describes the effect of mechanically fractionated flours from green bananas on the nutritional, physical and sensory attributes of two types of cakes (sponge and layer). A plausible 30% replacement of banana flour in the formulation of layer cakes is demonstrated, finding only a small d
• PMID 27765223

• Removing Trypan blue dye using nano-Zn modified Luffa sponge.

• Nadaroglu H1, Cicek S2, Gungor AA3.
• Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.Spectrochim Acta A Mol Biomol Spectrosc.2017 Feb 5;172:2-8. doi: 10.1016/j.saa.2016.08.052. Epub 2016 Aug 27.
• This study has presented specific features that are examined to remove the Trypan blue dye from the waste using Luffa sponge (LS) and modified Luffa sponge with zinc nanoparticles (ZnNPs). Peroxidase enzyme was obtained from Euphorbia amygdaloides plant and it was used with the green synthesis of Zn
• PMID 27592334

• One step photochemical synthesis of clean surfaced sponge-like porous platinum with high catalytic performances.

• Kong X1, Cao H2, Li C1, Chen X3.
• Journal of colloid and interface science.J Colloid Interface Sci.2017 Feb 1;487:60-67. doi: 10.1016/j.jcis.2016.10.005. Epub 2016 Oct 5.
• HYPOTHESIS: Template-free and surfactant-free strategies are highly desirable, which might be used for high efficient platinum catalyst developments.EXPERIMENTS: In this work, a facile one step photochemical synthesis method was developed to prepare sponge-like porous platinum. The present synthesis
• PMID 27744170

• Microbiome analysis shows enrichment for specific bacteria in separate anatomical regions of the deep-sea carnivorous sponge Chondrocladia grandis.

• Verhoeven JT1, Kavanagh AN1, Dufour SC2.
• FEMS microbiology ecology.FEMS Microbiol Ecol.2017 Jan;93(1). pii: fiw214. Epub 2016 Oct 17.
• The Cladorhizidae is a unique family of carnivorous marine sponges characterised by either the absence or reduction of the aquiferous system and by the presence of specialised structures to trap and digest mesoplanktonic prey. Previous studies have postulated a key role of host-associated bacteria i
• PMID 27756769

Japanese Journal

• Bromopyrrole Alkaloids from a Marine Sponge Agelas sp.

• Kusama Taishi,Tanaka Naonobu,Takahashi-Nakaguchi Azusa [他]
• Chemical and pharmaceutical bulletin 62(5), 499-503, 2014-05
• NAID 40020048729

• カイメン由来の海洋天然物と共生微生物の緊密な関係 (特集 天然物化学とケミカルバイオロジーの挑戦)

• 高田 健太郎,松永 茂樹,モリ テツシ [他]
• 化學工業 65(4), 311-318, 2014-04
• NAID 40020030321

• 海洋天然物furospinosulin-1由来のフォトアフィニティープローブ分子の合成 (特集 天然物化学とケミカルバイオロジーの挑戦)

• 古徳 直之
• 化學工業 65(4), 282-288, 2014-04
• NAID 40020030306

• New Nitrogenous Bisabolene-Type Sesquiterpenes from a Formosan Sponge Axinyssa sp.

• Liu Wangta,Liang Kai-Ju,Chiang Ching-Ying [他]
• Chemical and pharmaceutical bulletin 62(4), 392-394, 2014-04
• NAID 40020030139

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Related Pictures

---

★リンクテーブル★

リンク元	「100Cases 10」「海綿体」「海綿状」「spongy」「スポンジ」

「100Cases 10」

　　[★]

☆case10　背痛

■症例

27歳　女性

主訴：背中に突き抜ける？痛み(pain across her back)

現病歴：背中に広がる痛みを訴えて、27歳の女性が救急部に運ばれてきた。２日前に熱が出て背部痛が始まり、以降調子が悪い。痛みは増強している。6時間前に2度嘔吐した。

既往歴：3ヶ月前に合併症のない胆嚢炎。

・身体診断

調子が悪そうであり、紅潮している。体温：39.2℃。脈拍：120/分。血圧：104/68 mmHg。心血管系、呼吸器系に異常を認めず。腹部：全体的に圧痛。両側の腰部で著明な圧痛。

・検査

(血液生化学)

白血球↑、血清尿素↑、CRP↑

(尿検査)

タンパク：++、鮮血：+++、亜硝酸塩：++

尿の顕微鏡検査：(おそらく400倍の一視野に)赤血球>50、白血球>50

腹部X線：正常

■glossary

loin n. (pl)腰、腰部(→(adj.)lumbar)。(獣の)腰肉、ロイン。(pl)陰部、生殖器、性器

腸雑音、腸音、intestinal murmur、intestinal sound、bowel sound

urine microscopy 尿の顕微鏡検査

dysuria 排尿障害

urgency n. 切迫、急迫、危急。緊急、火急、焦眉の急。[pl]しつこい要求、懇願。せき立てる力、刺激

hydronephrosis 水腎症

-nephros 腎臓

-stomy 開口術

nephrostomy n. 腎瘻造設術、腎造瘻術、腎瘻術

obstructive urophathy 閉鎖性尿路疾患

intravenous fluid 静脈内輸液

commence vt. 始める、開始する。 vi. ～から始める、始まる(with)

urgently

eradication n. 根絶、撲滅

mimic vt. ～の物まねをする、まねて馬鹿にする。そっくりに[卑屈に]まねる。～によく似る

renal ultrasound 腎臓超音波検査

obstructive uropathy 閉塞性尿路疾患

polycystic kidney disease 多発性嚢胞腎

medullary sponge kidney 海綿腎

loin-pain hematuria syndrome 腰痛血尿症候群

■解説

(第1パラグラフ)疫学

　急性腎盂腎炎：男性より女性でmore common。尿路からの細菌の上行感染。リスク：妊娠、糖尿病、免疫低下者、尿路奇形(尿の腎臓への逆流。そして多分、狭窄していたりして結石で閉塞されやすいこともあると思う)

(第2パラグラフ)病態

　食欲不振、悪心、嘔吐と共に40℃の発熱が出ることがある。

　腎盂腎炎患者の中には膀胱炎の先行症状(排尿障害、頻尿、尿意切迫、血尿)がある人がいるけど、こういう下部尿路症状がいつも出現するわけではない。

　多くの腎盂腎炎患者は、先行する6ヶ月以内の膀胱炎の既往がある。

　老人の場合、非典型的な症状を示し、そして混乱した状態でやってくる。

　腎盂腎炎は他の病態によく似ている：急性虫垂炎、急性胆嚢炎、急性膵炎、下葉の肺炎

　普通、体表から見て腎臓の直上に前からも後ろからも圧痛を感じる。

　未治療の腎盂腎炎では敗血症になるかもしれない。

(第3パラグラフ)本ケースについて

　・CRP上昇は急性感染症を示唆

　・顕微鏡的血尿・タンパク尿、白血球増多は尿路の炎症を示す。

　・硝酸塩(nitrate, HNO3と何かの塩)から亜硝酸塩(nitrite, HNO2と何かの塩)への還元により細菌の存在が確認される。

　　覚え方：亜硝酸は(Oが一つ)足らないi(愛)

　　でも複雑です。

　　　HNO2　亜硝酸 nitrous acid, nitrite　。亜硝酸塩 nitrite

　　　HNO3　硝酸 nitric acid, nitrate　　 。硝酸塩 nitrate

(第4パラグラフ)管理

　・女性は入院すべき。

　・血液と尿の採取

　・静脈内輸液＋抗生物質で治療開始。微生物が同定されたら、感受性のある抗菌薬を使用する。初期治療ではゲンタマイシン、アンピシリン、シプロフロキサシンを用いる

　・腎臓エコー検査：尿路閉塞を除外するため。閉塞性尿路疾患では、激しい痛み、発熱、敗血症ショック、腎不全を伴う脳腎症を起こしうる。

　・尿路敗血症の経過で水腎症が疑われたら、合併症を防ぐために緊急に腎瘻を造設すべき

(第5パラグラフ)薬物治療

　・(腎結石など合併していない)腎感染症(ucomplicated renal infection)患者は抗生物質2週間のコースで治療すべき。

　・感染の根絶を確実にする治療が終わった後10-14日間は、反復して細菌培養をする。＜

　・尿路結石を有する感染症や腎瘢痕を有する患者では抗生物質6週間のコースが用いられる。

■鑑別診断のポイント

　腎盂腎炎は片側性、あるいは両側性の腰痛を引き起こす。

　腰部痛の鑑別診断：

　　閉塞性尿路疾患

　　腎梗塞：心疾患などで生じた血栓が腎動脈またはその分枝を閉塞し、その血管の支配領域が虚血性壊死に陥った状態。

　　腎細胞癌：腎尿細管上皮細胞より発生する悪性腫瘍

　　腎乳頭壊死：腎乳頭より腎髄質にかけて、その支配動脈の虚血により壊死を来したもの。 主として基礎疾患に糖尿病を有する人にみられ、しばしば急性腎盂腎炎などの尿路感染に伴って発症する。

　　腎結石：

　　糸球体腎炎：

　　多発性嚢胞腎：先天性かつ両側性に腎実質内に大小無数の嚢胞を発生する。 ほとんどが両側性で、貧血、顕微鏡的血尿、蛋白尿、高血圧といった症状を呈しながら腎機能が低下し、最終的には腎不全となる疾患

　　海綿腎：腎錐体における集合管の先天性嚢状拡張症。症状としては拡張した集合管に尿の停滞　→　感染・細かな結石ができる。

　　腰痛血尿症候群：若年女性に好発し、反復して出現する腰部から側腹部の強い疼痛と血尿を主徴とする病因不明の疾患。肉眼的血尿や軽度の蛋白尿がみられることもあるが、特異的な検査所見はなく、診断は他疾患の除外診断による

■KEYPOINT

・急性腎盂腎炎は下部尿路症状があったり無かったりする。

・腎臓超音波検査は尿路閉塞を否定するために、入院24時間後に行うべき。

・抗菌薬は、再発のリスクを最小限にするために、少なくとも2週間継続すべき。

□閉塞性尿路疾患(http://merckmanual.jp/mmpej/sec17/ch229/ch229a.htmlより引用)

• 閉塞性尿路疾患は正常な尿流を構造的または機能的に妨げ，ときに腎機能不全（閉塞性腎症）を起こすことがある。症状は，慢性の閉塞では認められないこともあるが，T11からT12にかけての皮膚分節に放散する疼痛，無尿，夜間頻尿または多尿がある。診断は閉塞のレベルによって，膀胱カテーテル法，超音波検査，CT，膀胱尿道鏡検査，膀胱尿道撮影または腎盂造影に基づく。治療は原因によって異なり，迅速なドレナージ，器具使用，外科手術（例，内視鏡法，砕石術）および/またはホルモン療法を必要とする場合がある。

□KUBの陰影から尿路結石成分の推定

　リン酸カルシウム(22.0)

　シュウ酸カルシウム(10.8)：シュウ酸カルシウム結石は，尿路結石のうちで最も頻度が高く（70～80％），シュウ酸カルシウム結石の約半数はリン酸カルシウムとの混合結石である。

　リン酸マグネシウムアンモニウム(4.1)：ストラバイト結石：尿素分解菌(Proteus　、Klebsiella　、Pseudomonas　)による尿路感染が原因で、尿素が分解されアンモニアとなると尿がアルカリ性となり、リン酸マグネシウムアンモニウム結石が形成される。

　シスチン(3.7)：ホモシスチン尿症

　尿酸(1.4)：痛風

　キサンチン(1.4)：プリン体

□多嚢胞腎

　常染色体劣性多発性嚢胞腎：ARPKD

　　旧名：幼児型嚢胞腎

　常染色体優性多発性嚢胞腎：ADPKD

　　旧名：成人型嚢胞腎

「海綿体」

　　[★]

英

sponge, corpus cavernosum, cavernous body

• 陰茎海綿体 corpus cavernosum penis
• 尿道海綿体 corpus spongiosum penis

「海綿状」

　　[★]

英

spongiform、sponge、spongy、cancellous

関

海綿、海綿質、海綿体、スポンジ

「spongy」

　　[★]

• 海綿状の、海綿質の

関

cancellous、sponge、spongiform、spongiosa

　 　 　

「スポンジ」

　　[★]

英

sponge

関

海綿、海綿質、海綿状、海綿体、海綿動物