Regeneration
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Research study 1
 

drawing of oral surface of feather star showing locations where amputations are donephotograph of feather star Florometra serratissima swimming with 3 or more of its arms in process of regeneration
Regeneration is a common feature in classes of echinoderms whose members bear arms (crinoids, ophiuroids, and asteroids) and undergo autotomy. It is not uncommon for individuals in these classes to have arms in varying states of regrowth.  For example, a survey of 261 individuals of Florometra serratissima in Barkley Sound, British Columbia shows that roughly 80% have at least one regenerating arm.  Arm loss could be caused by wave action, moving debris, physiological stressors, or disturbance by animals. The arms are released at an autotomy line located approximately in the position indicated by "arm stump" in the drawing on the Right.

Rates of regeneration of arms in F. serratissima is studied at the Bamfield Marine Sciences Centre by amputating different numbers of arms from individuals, caging them at 25m depth, and monitoring regrowth at regular intervals.  The arms are removed at a point close to a natural autotomy line, leaving a 1-cm stump. Results show that arm replacement is linear over time (see graph lower Left). Regeneration times are similar regardless of number of arms removed (up to 5).  Thus, with more arm mass to regenerate the rate of tissue replacement is actually greater as more arms need to be replaced.  Complete arm regeneration in the field takes about 9mo. Mladenov 1983 Can J Zool 61: 2873.

NOTE a description of the process of autotomy is available at LEARN ABOUT FEATHER STARS: PREDATORS & DEFENSES: AUTOTOMY

NOTE field temperature is not mentioned by the author, but is likely to be about 5-8oC

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