by Piter Kehoma Boll
A fascinating group of animals that has not yet joined the Friday Fellows are the sponges. Different from all other animals, sponges have a unique body structure that behaves more like a plant or fungus. They grow in irregular or radial ways and are usually branched. More than that, they have thousands of small mouths along their bodies, called pores, that suck water from the environment in order to filter food from it.
But let’s talk about our species. Living in the Caribbean Sea, its name is Callyspongia vaginalis, commonly known as branching vase sponge. Its usual shape is that of a tube or set of tubes, sometimes branched, that may reach several centimeters in length and usually abour 3 cm in diameter. The color may vary from pink or lavender to duller colors, such as brown or gray.
As most sponges, the branching vase sponge feeds on small particles and microorganisms that it filters from water. As the concentration of particles in the water increases with depth, organisms growing deeper usually grow faster due to the higher food availability.
The main predators of the branching vase sponge are fishes. They actually act more like herbivores eating plants, as they don’t eat the whole sponge and usually do not kill it, but bite its surface, taking off pieces.
Bristlestars, especially of the genus Ophiothrix, such as Ophiothrix lineata, are frequently found living inside the main cavity of the sponge. There, these animals find shelter from predators and, at night, when the environment is safer, they extend their arms outside and clean the sponge from large organic particles, feeding on them. It’s a mutually benefitial association.
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EOL – Encyclopedia of Life. Callyspongia vaginalis. Available at <http://eol.org/pages/1163688/overview>. Access on January 12, 2017.
Hendler, G. (1984). The Association of Ophiothrix lineata and Callyspongia vaginalis: A Brittlestar-Sponge Cleaning Symbiosis? Marine Ecology, 5 (1), 9-27 DOI: 10.1111/j.1439-0485.1984.tb00304.x
Hoppe, W. (1988). Growth, regeneration and predation in three species of large coral reef sponges Marine Ecology Progress Series, 50, 117-125 DOI: 10.3354/meps050117
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