Tuesday, May 18, 2010

Battle of the Titans! Starfish Vs. FOOD Videos!!

Agh! Busy this week... But here's some cool videos that demonstrate the diversity of feeding in asteriid starfish!

Marthasterias & that CRUSHING feeling!

Here's the tropical-temperate Atlantic Marthasterias glacialis in the Canary Islands about to devour what I think is Paracentrotus lividus (or some other urchin) using "crushing predation" as described in a recent paper by Gianguzza et al. (2009) in Marine Biology.

Based on their account, this feeding is more then simply using their stomach to devour the soft parts-it uses its body to CRUSH the test (the round "shell" that makes up the body)!! It was previously thought that only fish utilized such a strategy...

Starfish VS. SCALLOP!
Scallops and other shelled mollusks are often prey to asteriid starfish and have VERY strong behavioral responses when they detect them nearby. This has been observed for awhile-for example in this paper by Thomas and Gruffydd (1971).

Here's Marthasterias again..but placed next to the scallop, Pecten maximus. Scallops can SMELL when known predators are nearby..and they can use high pressure jets in their water siphons to escape...like so... But ONLY when specific predatory species are around.

This also looks like Marthasterias...

and here is the North Pacific Sunflower star, Pycnopodia helianthoides doing the same to some Pacific scallop species....

And here is Pycnopodia again! this time harassing what looks like a cockle! Note the extreme escape response as the foot goes into red-alert mode and PUSHES the body away from the oncoming starfish!

More Soon!

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