Encrusting Star Sponge
Halisarca caerulea
Also known as: Encrusting Sponge, Marine Sponge
- Encrusting Sponge
- Marine Sponge
Overview
The encrusting star sponge (Halisarca caerulea) is a wafer-thin Caribbean sponge marked with star-shaped patterns of canals. It spreads over reefs as a blue crust only about 1.5mm thick, and it filters huge amounts of water yet hardly grows at all.
It lives over coral and rocky reefs of the Caribbean Sea.
Appearance
The surface is smooth, slightly slimy and fleshy to the touch, with a net-like pattern from bundles of collagen fibres in the skin. Its calling card is the star-shaped groups of surface canals, spaced regularly across the sponge with smooth patches between them. Each star has an opening about 3mm across at its centre, and up close these can look like tiny volcanoes. Living specimens are bright blue.
Feeding
Like other sponges it draws water in through small pores, strains out bacteria and organic particles, then pumps the water back out. Caribbean waters hold very few nutrients, so it has to move a great deal of water to get what it needs. Going by the carbon it takes up it ought to grow fast, but instead it throws off cells nearly as quickly as it makes them, and the debris feeds other animals.
Notes & fun facts
- DID YOU KNOWIts filtering cells divide every five or six hours, yet the sponge barely grows because it sheds them almost as fast as it makes them.
- DID YOU KNOWResearchers think this rapid turnover may help it cope with pollutants and toxins taken in while filter feeding.
- DID YOU KNOWThe shed cells return carbon to the water as detritus that other animals can eat, part of what is called the sponge loop.
How to identify
Habitat & where to find it
- Range · Caribbean
- Country only · 1
Found over coral and rocky reefs of the Caribbean Sea.
Adult photos 1
Discussion
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Deep dive
Taxonomy
- kingdomAnimalia
- phylumPorifera
- classDemospongiae
- orderChondrillida
- familyHalisarcidae
- genusHalisarca
- speciesHalisarca caerulea Vacelet & Donadey, 1987
SourcesWoRMSSeaLifeBase
Morphology
A thinly encrusting sponge about 1.5mm thick with a fleshy texture, a skin strengthened by collagen bundles, and no spicules. Its long tubular choanocyte chambers are sometimes branched. Openings about 3mm across sit at the centre of conspicuous star-shaped canal systems.