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Carnivory hot buttons for carnivory part of Biology of Caribbean Coral Reefs website hot button for zooplanktivore part of BCCR hot button for spongivore part of BCCR hot button for corallivores & other cnidivores part of BCCR hot button for gorgonivores part of BCCR hot button for benthic invertebrate-eaters part of BCCR hot button for piscivores part of BCCR
This part of carnivory deals with spongivores, that is, with coral-reef organisms that eat sponges. Other topics relating to carnivory on coral reefs can be accessed via the icons.
 
 

Carnivory: spongivores: sea stars that eat sponges

Major predators of sponges are vertebrates, including a variety of fishes and turtles, but several types of invertebrates, such as sea stars and several types of gastropods, also eat sponges. Sea stars, nudibranchs, & snails will be considered here, while FISHES and TURTLES are dealt with in their own sections.

 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of cushion stars

"Sea stars are not common on Caribbean reefs. It's best to look for them in the back-reef area, especially among seagrass beds. Here's quite a few, in a sandy area close to shore...cushion stars! I wonder what they're eating?" - Turks & Caicos 2005

NOTE Oreaster reticulatus

 
 

photograph of cushion star Oreaster reticulatus
In the San Blas Islands of Panama about 60% of the diet of cushion sea stars is sponges, comprising over 50 different species. Most live within the sea stars' seagras-meadow and rubble-flat habitat, but a few species are transported there in waves and currents as fragments from fore-reef habitats. Wulff 1995 Mar Biol 123: 313.

 

 

 

Cushion sea star Oreaster
reticulatus
0.5X

  photo/drawing showing stomach arrangement in a cushion star Oreaster reticulatusSea stars have an unusual method of feeding. They have 2 stomachs. The outermost one is everted onto the substratum or into living prey, and tissues are digested in situ. The liquefied food matter is then moved into the innermost stomach and distributed to 5 pairs of digestive glands in the 5 arms. It takes about 36h for digestion of a sponge fragment to be completed. What remains is undigested magnifying glass showing sponge spicules after sea-star digestionskeletal-spicule matter. Wulff 1995 Mar Biol 123: 313.
 
 

Carnivory: spongivores: nudibranchs & snails that eat sponges

 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of sea slug Elysia crispata taken from a video

"Most sea slugs are hiding during the day and only come out at night. If you see one, though, chances are high that it eats sponges...not this lettuce slug, though, it eats plant juices." - Turks & Caicos 2003.

NOTE the lettuce slug, Elysia crispata, actually requires light to meet the energy needs of photosynthetic symbionts obtained from its food. More on this subject can be found at NUTRITION: PRIMARY PRODUCTIVITY: INVERTEBRATES: SNAILS

 
 

photograph of nudibranch Geitodoris mavis courtesy Anne Dupont, Florida
About 130 species of sea slugs (nudibranchs) live in the Caribbean region. Some 70% of these eat sponges, while the remainder eat bryozoans, hydroids, tunicates, and other invertebrate prey. Gosliner 1997 Proc 7th Int Coral Reef Symp Vol. 2: 702. Photograph courtesy Anne Dupont, Florida.

 

 

Sponge-eating dorid nudibranch, possibly Gaitodoris mavis.
The mouth and radula are located at the end of the proboscis,
which is extended outwards in this specimen. The tufty
structures at the back end are the ctenidia or gills 1X

 

photograph of nudibranch Discodoris mortensi courtesy Sandra Millen, University of British ColumbiaClose examination of fresh feces of this nudibranch discloses numerous spicules of its sponge prey, mostly broken but some, surprisingly, intact. Photograph courtesy Sandra Millen, University of British Columbia.

 

 

 

 

Caribbean nudibranch
Discodoris mortensi 2X

 
 

photographs of a gray cowrie Luria cinerea with one of its prey sponges, the tube sponge Aplysina fistularisCaribbean olive shells are most often seen just as dead shells on the beach, but if you examine tube sponges such as the yellow tube-sponge Aplysina fistularis at night, especially ones with evident damage, you may see live gray cowries Luria (Cypraea) cinerea crawling on and in them feeding on their tissues. Persistent feeding by the cowries creates fissures and wounds that are slow to heal, and often impart an overall diseased appearance to the sponge. Pawlik & Deignan 2015 Coral Reefs 34: 663.

 

 

 

The authors note that this particular yellow tube-sponge
Aplysina fistularis
contained several juvenile and adult gray
cowries Luria cinerea within the main chamber. Inset 3X

 
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