User Contributed Dictionary
Noun
sponges- Plural of sponge
Verb
sponges- third-person singular of sponge
Extensive Definition
'' The sponges or poriferans (from Latin
porus
"pore" and ferre "to
bear") are animals of the
phylum Porifera ().
Porifera translates to "Pore-bearer". They are primitive, sessile, mostly marine, water dwelling filter
feeders that pump water through their bodies to filter out
particles of food matter. Sponges represent the simplest of
animals. With no true tissues (parazoa), they lack muscles, nerves, and internal organs.
Their similarity to colonial choanoflagellates
shows the probable evolutionary jump from unicellular to multicellular organisms.
However, recent genomic studies suggest they are not the most
ancient lineage of animals, but may instead be secondarily
simplified.
There are over 5,000 modern species of sponges
known, and they can be found attached to surfaces anywhere from the
intertidal
zone to as deep as 8,500 m (29,000 feet)
or further. Though the fossil record of sponges dates
back to the Neoproterozoic
Era, new species are still commonly discovered.
Anatomy and morphology
Sponges have several cell types:- Choanocytes (also known as "collar cells") function as the sponge's digestive system, and are remarkably similar to the protistan choanoflagellates. The collars are composed of many microvilli and are used to filter particles out of the water. The beating of the choanocytes’ flagella creates the sponge’s water current.
- Porocytes are tubular cells that make up the pores into the sponge body through the mesohyl.
- Pinacocytes which form the pinacoderm, the outer epidermal layer of cells. This is the closest approach to true tissue in sponges
- Myocytes are modified pinacocytes which control the size of the osculum and pore openings and thus the water flow.
- Archaeocytes (or amoebocytes) have many functions; they are totipotent cells which can transform into sclerocytes, spongocytes, or collencytes. They also have a role in nutrient transport and sexual reproduction.
- Sclerocytes secrete calcareous siliceous spicules which reside in the mesohyl.
- Spongocytes secrete spongin, collagen-like fibers which make up the mesohyl.
- Collencytes secrete collagen.
- Spicules are stiffened rods or spikes made of calcium carbonate or silica which are used for structure and defense.
- Cells are arranged in a gelatinous non-cellular matrix called mesohyl
Asconoid sponges are tubular with a central shaft
called the spongocoel. The beating of
flagella forces water into the spongocoel through pores in the body
wall. Choanocytes line the spongocoel and filter nutrients out of
the water.
Syconoid sponges are similar to asconoids. They
have a tubular body with a single osculum, but the body wall is
thicker and more complex than that of asconoids and contains
choanocyte-lined radial canals that empty into the spongocoel.
Water enters through a large number of dermal ostia into incurrent
canals and then filters through tiny openings called prosopyles into the radial
canals. Their food is ingested by the choanocytes. Syconoids do not
usually form highly branched colonies as asconoids do. During their
development, syconoid sponges pass through an asconoid stage.
Leuconoid sponges lack a sperm and instead have
flagellated chambers, containing choanocytes, which are led to and
out of via canals.
It should be noted that these 3 body grades are
useful only in describing morphology, and not in classifying sponge
species, althought the asconoid and syconoid construction is
present in Calcarea only.
Physiology
Sponges have no true circulatory system; instead, they create a water current which is used for circulation. Dissolved gases are brought to cells and enter the cells via simple diffusion. Metabolic wastes are also transferred to the water through diffusion. Sponges pump remarkable amounts of water. Leuconia, for example, is a small leuconoid sponge about 10 cm tall and 1 cm in diameter. It is estimated that water enters through more than 80,000 incurrent canals at a speed of 6cm 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 3.6cm per hour. Such a flow rate allows easy food capture by the collar cells. All water is expelled through a single osculum at a velocity of about 8.5 cm/second: a jet force capable of carrying waste products some distance away from the sponge.Sponges of the family Cladorhizidae (order
Poecilosclerida, class Demospongiae) are species usually found in
deep water, but also in littoral caves
in the Mediterranean
(Asbestopluma hypogea), that have become carnivorous, using a
strategy that has much in common with what is found in carnivorous
plants such as sundew.
When small crustaceans comes in contact with their surface, they
get captured by a sticky substance, or in the case of the
Mediterranean species by spicules modified into raised hook-shaped
spines, and then digested by migrating cells which soon covers the
prey. This lifestyle has caused the loss of their aquiferous system
and the choanocytes, resulting in forms like the ping-pong tree
sponge (Chondrocladia lampadiglobus), who don't look like typical
sponges.
Taxonomy
Sponges are traditionally divided into classes based on the type of spicules in their skeleton. The three classes of sponges are bony (Calcarea), glass (Hexactenellida), and spongin (Demospongiae). Some taxonomists have suggested a fourth class, Sclerospongiae, of coralline sponges, but the modern consensus is that coralline sponges have arisen several times and are not closely related. In addition to these four, a fifth, extinct class has been proposed: Archaeocyatha. While these ancient animals have been phylogenetically vague for years, the current general consensus is that they were a type of sponge. Although 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.Sponge taxonomy is an area of active research,
with molecular studies improving our understanding of their
relationship with other animals.
Basal lineage?
Sponges are among the simplest animals. They lack gastrulated embryos, extracellular digestive cavities, nerves, muscles, tissues, and obvious sensory structures, features possessed by all other animals. In addition, sponge choanocytes (feeding cells) appear to be a homologous to choanoflagellates, a group of unicellular and colonial protists that are believed to be the immediate precursors of animals. The traditional conclusion is that sponges are the basal lineage of the animals, and that features such as tissues developed after sponges and other animals diverged. Sponges were first assigned their own subkingdom, the Parazoa, but more recent molecular studies suggested that the sponges were paraphyletic to other animals, with the eumetazoa as a sister group to the most derived:Either way, sponges have long been considered
useful models of the earliest multicellular ancestors of
animals.
...or secondarily simplified?
However, a phylogenomic study in 2008 of 150 genes in 21 genera suggests that the ctenophora are the most basal lineage of the 21 taxa sampled, and that sponges—or at least those lines of sponges investigated so far—are not primitive, but secondarily simplified, having lost tissues and other eumetazoan characteristics from their common ancestor.Geological history
The fossil
record of sponges is not abundant. Some fossil sponges have
worldwide distribution, while others are restricted to certain
areas. Sponge fossils such as Hydnoceras and
Prismodictya
are found in the Devonian rocks of
New York
state. In Europe the Jurassic limestone of the Swabian Alb
are composed largely of sponge remains, some of which are well
preserved. Many sponges are found in the Cretaceous Lower
Greensand and Chalk
Formations of England, and in
rocks from the upper part of the Cretaceous period in France. A famous
locality for fossil sponges is the Cretaceous Faringdon Sponge
Gravels in Faringdon,
Oxfordshire in
England. An
older sponge is the Cambrian Vauxia. Sponges have
long been important agents of bioerosion in shells and
carbonate rocks. Their borings extend back to the Ordovician in
the fossil record.
Fossil sponges differ in size from 1 cm (0.4
inches) to more than 1 meter (3.3 feet). They vary greatly in
shape, being commonly vase-shapes (such as Ventriculites),
spherical (such as Porosphaera), saucer-shaped (such as
Astraeospongia), pear-shaped (such as Siphonia), leaf-shaped (such
as Elasmostoma), branching (such as Doryderma), irregular or
encrusting.
Detailed identification of many fossil sponges
relies on the study of thin sections.
Ecology
Modern sponges are predominantly marine, with
some 150 species adapted to freshwater environments. Their habitats
range from the inter-tidal zone to depths of 6,000 metres (19,680
feet). Certain types of sponges are limited in the range of depths
at which they are found. Sponges are worldwide in their
distribution, and range from waters of the polar regions to the
tropical regions. Sponges are most abundant in both numbers of
individuals and species in warmer waters.
Adult sponges are largely sessile, and live in an
attached position. However, it has been noted that certain sponges
can move slowly by directing their water current in a certain
direction with myocytes. The greatest numbers of sponges are
usually to be found where a firm means of fastening is provided,
such as on a rocky ocean bottom. Some kinds of sponges are able to
attach themselves to soft sediment by means of a root-like base.
Sponges also live in quiet clear waters, because if the sediment is
agitated by wave action or by currents, it tends to block the pores
of the animal, lessening its ability to feed and survive.
Recent evidence suggests that a new disease
called
Aplysina red band syndrome (ARBS) is threatening sponges in the
Caribbean.http://www.practicalfishkeeping.co.uk/pfk/pages/item.php?news=1113
Aplysina red band syndrome causes Aplysina to develop one or more
rust-coloured leading edges to their structure, sometimes with a
surrounding area of necrotic tissue so that the lesion causes a
contiguous band around some or all of the sponge's branch.
Asexual reproduction is through internal and
external budding.
External budding occurs when the parent sponge grows a bud on the
outside of its body. This will either break away or stay connected.
Internal budding occurs when archaeocytes collect in the mesohyl
and become surrounded by spongin. The internal bud is
called a gemmule, and
this is seen only in the freshwater sponge family, the
Spongillidae. An asexually reproduced sponge has exactly the same
genetic material as the parent.
In sexual reproduction, sperm are dispersed by water
currents and enter neighboring sponges. All sponges of a particular
species release their sperm at approximately the same time.
Fertilization occurs internally, in the mesohyl. Fertilized oocytes
develop within the mesohyl. Cleavage stages are highly varied
within and between groups, sometimes even within a single species.
Larval development usually involves an odd type of morphogenetic
movement termed an inversion of layers. When this occurs in some
species (for example, in Sycon coactum ), the larva flips into the
choanocyte chamber, and then can emerge via the water canal system
and out through the osculum.
Although sponges are hermaphroditic (both male
and female), they are not self-fertile. Most sponges are sequential
hermaphrodites, capable of producing eggs or sperm, but not both at
the same time.
Use
By dolphins
In 1997, use of sponges as a tool was described in Bottlenose Dolphins in Shark Bay. 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 behaviour, known as sponging, has only been observed in this bay, and is almost exclusively shown by females. This is the only known case of tool use in marine mammals outside of Sea Otters. An elaborate study in 2005 showed that mothers most likely teach the behaviour to their daughters.By humans
Skeleton as absorbent
In common usage, the term sponge is applied to the skeleton of the animal, from which the tissue has been removed by maceration and washing, leaving just the spongin scaffolding. Calcareous and siliceous sponges are too harsh for similar use. Commercial sponges are derived from various species and come in many grades, from fine soft "lamb's wool" sponges to the coarse grades used for washing cars.The manufacture of rubber-, plastic- and cellulose-based synthetic
sponges has significantly reduced the commercial sponge fishing industry in recent
years.
The luffa "sponge", also spelled
loofah, commonly sold for use in the kitchen or the shower, is not
derived from an animal sponge, but from the locules of a gourd (Cucurbitaceae).
Antibiotic compounds
Sponges have medicinal potential due to the presence of antimicrobial compounds in either the sponge itself or their microbial symbionts.Bibliography
- Animal Diversity
- New disease threatens sponges, Practical Fishkeeping
References
Further reading
- Berguist, P. R. 1998. "The Porifera" (pp. 10-27), in D. T. Anderson (ed.) Invertebrate Zoology. (A brief treatment)
- Berguist, P. R. 1978. Sponges Hutchinson, London.
See also
External links
- Queensland Museum FAQ about sponges
- Sponge Guide from Queensland Museum, John Hooper
- World Porifera database, The World list of extant sponges, includes a searchable database.
- Carsten's Spongepage, Information on the ecology and the biotechnological potential of sponges and their associated bacteria
- The Sponge Reef Project
- Bioerosion website at The College of Wooster
- Dolphin Moms Teach Daughters to Use Tools National Geographic article with image
- http://fcit.usf.edu/FLORIDA/lessons/tarpon/tarpon.htm - History of Tarpon Springs, Florida sponge industry
sponges in Arabic: إسفنجيات
sponges in Bulgarian: Водни гъби
sponges in Catalan: Porífer
sponges in Czech: Houbovci
sponges in Welsh: Sbwng
sponges in Danish: Svampedyr
sponges in German: Schwämme
sponges in Estonian: Käsnad
sponges in Modern Greek (1453-): Σπόγγος
sponges in Spanish: Porifera
sponges in Esperanto: Spongulo
sponges in Basque: Belaki
sponges in Persian: اسفنج دریایی
sponges in French: Porifera
sponges in Galician: Porifera
sponges in Korean: 해면동물
sponges in Croatian: Spužve
sponges in Ido: Sponjo
sponges in Indonesian: Porifera
sponges in Icelandic: Svampdýr
sponges in Italian: Porifera
sponges in Hebrew: ספוגיים
sponges in Luxembourgish: Schwämm
sponges in Lithuanian: Pintys
sponges in Hungarian: Szivacsok
sponges in Macedonian: Сунѓери
sponges in Dutch: Sponsdieren
sponges in Japanese: 海綿
sponges in Norwegian: Svamper
sponges in Norwegian Nynorsk: Svampar
sponges in Occitan (post 1500): Porifera
sponges in Polish: Gąbki
sponges in Portuguese: Porifera
sponges in Quechua: Puqyala
sponges in Russian: Губки
sponges in Simple English: Sponge
sponges in Slovak: Hubky
sponges in Slovenian: Spužve
sponges in Serbian: Сунђери
sponges in Serbo-Croatian: Spužve
sponges in Finnish: Sienieläimet
sponges in Swedish: Svampdjur
sponges in Thai: ฟองน้ำ
sponges in Turkish: Süngerler
sponges in Ukrainian: Губки
sponges in Chinese: 多孔动物门