^Q y PROTECTIVE ADAPTATIONS McATEE 15 



Mcintosh comments interestingly on the enemies of echinoderms : 

 " The colours of Echinoderms are often most conspicuously bright," 

 but Hippasterias, which is brilliant orange-red, is eaten by gulls, 

 cod, catfishes and by other starfishes. " The sand-stars (e. g. Ophiura 

 laccrtosa) are often tinted of a hue resembling their surroundings, 

 vet they and the more brightly tinted forms are common in the 

 stomachs of fishes and are eagerly devoured by gulls when stranded 

 on the beach." " The brown and purple hues of sea-cucumbers may 

 in some way subserve protection .... yet both they and the trans- 

 parent forms are found in the stomachs of fishes." (Ann. Mag. Nat. 

 Hist. 7th ser., vol. 7, pp. 225-226, 1901.) 



Discussion.— Y.chmoderms have a number of protective devices 

 but also it would appear, numerous and effective enemies. Birds prey 

 upon this group to fully as large an extent as could be expected, con- 

 sidering the slight degree to which they come in contact with echino- 

 derms. 



It should be noted that while practically all starfishes and sea- 

 urchins have similar protective adaptations, some are very gaudily, 

 others modestly colored ; in one case or the other, the natural selec- 

 tion theory as to the connection between special defenses and color- 

 ing is untenable. The sea-urchins with calcareous tests, abundaiit 

 spines, and pedicellariae seem unusually well defended, but that this 

 does not mean freedom from enemies is shown by the great fecundity 

 of sea-urchins, individuals of some species, e. g., Echinus escnlcntus, 

 yielding 20,000,000 eggs per season. 



ANNULATA (WORMS) 



Protective adaptations.— The chaetopods including the most com- 

 mon marine worms and the majority of earthworms have chitinous 

 setae on all segments of the body. The earthworms are habitual bur- 

 rowers, and some of both fresh- and salt-water annelids live in tubes. 

 A few in each group are phosphorescent, and many of the marine 

 worms are highly colored. A. R. Wallace says:' "Among the crea- 

 tures which probably have warning colors as a sign of inedibility are 

 .... those curious annelids the Nereis and the Aphrodite or sea- 

 mouse." 



It should 1)e noted however that many of the brightly colored fornis 

 live in burrows or tubes, thus taking care not to advertise their 

 " inedibility." Leeches sometimes have strongly contrasting color, as 

 for example greenish with red and black spots. 



' Darwinism, p. 266, 1896. 

 2 



