Armina californica - feeding

September 26, 2007
From: Jan Kocian


Hello Bill
I found Armina californica crowding on the sea pen Ptilosarcus gurneyi. My question is: When the sea pen retracts its polyps and curls into a fraction of its normal size, do the slugs still get their food ?

Locality: Possession Beach, Whidbey Island, 50 feet, Washington, USA, Eastern North Pacific, 19 September 2007, sandy slope. Length: 6 cm. Photographer: Jan Kocian.

Thank you.

honkoc@hotmail.com

Kocian, J, 2007 (Sep 26) Armina californica - feeding. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20780

Dear Jan,

Thanks for these great photos. When a cnidarian polyp is fully extended its volume must consist of 90% water - or even more. When it contracts the water is just forced into another part of the body, but it means the contracted part has much more 'meat' per volume, so I guess as long as the sea pen body doesn't contract out of reach of the slug, the Armina doesn't lose any of its potential food.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Sep 26). Comment on Armina californica - feeding by Jan Kocian. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20780

Factsheet

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