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/20780Dear 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
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