Diversity
There are about 400 described species of sponges in the
Calcarea
group.
Geographic Range
Calcarea
sponges are found throughout the oceans, but are mainly in temperate areas.
- Biogeographic Regions
- arctic ocean
- indian ocean
- atlantic ocean
- pacific ocean
- mediterranean sea
Habitat
Exclusively marine and mainly in temperate regions,
Calcarea
sponges are usually found in shallower, sheltered waters less than 1000 m. In tropical
regions they are associated with coral reefs.
- Habitat Regions
- temperate
- tropical
- saltwater or marine
- Other Habitat Features
- intertidal or littoral
Physical Description
Calcarea
is the only class with asconoid and syconoid construction. All others have leuconoid
construction. The calcium carbonate spicules are only megascleres, or large structural
spicules. Other groups of sponges have microscleres, which are smaller reinforcing
spicules. Most
Calcarea
are 10 cm less in height, and are dull in color, although some colorful species are
known.
- Other Physical Features
- ectothermic
- heterothermic
Development
Reproduction occurs asexually by budding and sexually. Development of fertilized eggs takes place within the sponge. The larval stage has outer flagellated cells, often with spicules. The young break out of the parent's mesohyl, and become free swimming larvae, but not for more than two days.
Sponges have different amoeboid cells in the mesohyl. Acheocytes are large cells
with large nuclei. These cells are totipotent, meaning they can develop into any
cell type. Sclerocytes, also in the mesohyl, accumulate calcium to produce spicules.
Three sclerocytes will fuse to form spicules in intercellular spaces.
- Development - Life Cycle
- indeterminate growth
Reproduction
Most all sponges can reproduce asexually, by regenerating tissues. Sponges also reproduce
sexually. Being hermaphroditic, sperm and eggs can be reproduced, sequentially or
at the same time. Choanocytes give rise to egg and sperm cells, and archaeocyte cells
also give rise to egg cells. Sperm and eggs are released in the water, and most species
cross fertilize. Fertilized eggs will develop into free-swimming larvae.
- Key Reproductive Features
- simultaneous hermaphrodite
- sequential hermaphrodite
- sexual
- asexual
- fertilization
- viviparous
There is no parental investment beyond release of gametes.
Behavior
Members of
Porifera
are sessile since they are attached to the substrate. However, some sponges may
move as amoeboid cells at the base move.
- Key Behaviors
- sessile
Communication and Perception
Sponges will react by closing ostia or oscula, either because of direct physical stimulation
or when suspended particles within the sponge are too large or highly concentrated.
However, there are no known nerve structures. However, some sponges may respond to
electrical impulses.
Food Habits
Because of the simple cells that make up sponges, cell types and water currents used by the sponges to obtain food have been extensively studied. Sponges in general use flagellated cells called choanocyte cells to create a current. Choanocytes are located in the interior part of the sponge. In the asconoid structure, the water is drawn in through the ostium (outer pores), goes through the spongocoel or atrium, and out the osculum (the opening in the top of the sponge). Outer pores are 50 micrometers or less, so larger particles and animals are not ingested.
As food or particles are moved through the sponges, amoemoid cells surround and engulf
it (pinocytosis and phagocytosis). Particles are caught in the collar part of the
choanocyte cells.
- Primary Diet
- planktivore
- detritivore
- Foraging Behavior
- filter-feeding
Predation
Sponges are preyed on by many animals. Spicules, and other compounds, including potential
biotoxins, probably discourage most predators.
Ecosystem Roles
Sponges in general may make up a significant portion of the benthic biomass. For
example, in Antarctica, at depths of 100-200 m, 75 per cent of the benthic biomass
are sponges.
- Ecosystem Impact
- creates habitat
Economic Importance for Humans: Positive
Sponges have been harvested for centuries by many civilizations. Compounds produced
by sponges are being explored for pharmaceuticals.
- Positive Impacts
- body parts are source of valuable material
Conservation Status
Sediments effect sponges although they are resistant to hydrocarbons (including detergents)
and heavy metals. Particular species have been overharvested.
Other Comments
Although
Calcarea
is considered the primitive group, and are the only sponges with asconoid and synconoid
construction, the asconoid and synconoid forms are not necessarily considered primitive
conditions.
Additional Links
Contributors
Renee Sherman Mulcrone (author).
- Arctic Ocean
-
the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.
- Atlantic Ocean
-
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
- Pacific Ocean
-
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- benthic
-
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
- reef
-
structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- intertidal or littoral
-
the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- indeterminate growth
-
Animals with indeterminate growth continue to grow throughout their lives.
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- asexual
-
reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- sessile
-
non-motile; permanently attached at the base.
Attached to substratum and moving little or not at all. Synapomorphy of the Anthozoa
- chemical
-
uses smells or other chemicals to communicate
- electric
-
uses electric signals to communicate
- filter-feeding
-
a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.
- planktivore
-
an animal that mainly eats plankton
- detritivore
-
an animal that mainly eats decomposed plants and/or animals
References
Bamfield Marine Sciences Centre, 2004. "Porifera" (On-line). Ocean Link. Accessed January 13, 2005 at http://oceanlink.island.net/ask/porifera.html#anchor22429 .
Barnes, R. 1987. Invertebrate Zoology . Orlando, Florida: Dryden Press.
Brusca, R., G. Brusca. 2003. Invertebrates . Sunderland, Massachusetts: Sinauer Associates, Inc..
Wörheide, G. 2002. "Calcarea Introduction" (On-line). Gert Wörheide's homepage about geobiology. Accessed January 13, 2005 at http://wwwuser.gwdg.de/~gwoerhe/calcarea_introduction.html .