Long Beach Aquarium of the Pacific, Long Beach, CA April 18, 2003
Jennings (1907) made the remarkable observation that the
fragile rainbow seastar, Astrometis sertulifera (but misidentified as Asterias forreri by Jennings),
can use its forceps-like pedicellariae to capture active prey that are sometimes as large as the seastar itself.
With its large cushions bearing numerous tiny pedicellariae, it can catch small crabs, sand
crabs, and even fishes to be later
transferred to the mouth and eaten. A. sertulifera also has its own predators, at least in the more southern part of its range
on the southern portion of the Baja California peninsula where it co-occurs with the predatory sea star,
Heliaster kubiniji.
Jennings observed that A. serulifera has an escape response to
H. kubiniji, but gets eaten when confined in lab aquaria.
Jennings performed other classic studies in his La Jolla lab aquaria near San Diego.
Jennings studied their fairly rapid movement to explore a
lab aquarium before settling down. Jennings found that they prefer shaded areas, avoiding strong light and increasing in their movement when exposed to a
new beam of light. Jennings was apparently able to train seastars to turn themselves over using a particular arm to right themselves,
but found that sea stars are like students to try to memorize for exams; they don't retain what they learn. They are slow to learn new
habits and revert to be normal seastars within a few days of training. Jennings pessimistic remarks were also quoted by Feder (1980):
'It would now be
possible...to develop...educational methods for the starfish. By begininning with young specimens, it is probable that
striking results would be reached. Such an investigation would require steady application to extremely dull and tedious work,
for a long period.'
Feder, H. M. 1980. Chapter 8 - Asteroidea: The sea stars. Pp. 117-135, in (R. M. Morris, D. P. Abbott and E. C. Haderlie, eds.) Intertidal Invertebrates of California. Stanford Univ. Press, Palo Alto.
Jennings, H. S. 1907. Behavior of the starfish, Asterias forreri de Loriol. Univ. Calif. Publ. Zool. 4: 53-185.
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Image by D.J. Eernisse © 2003 Caption updated by D.J. Eernisse © 2015