NATURAL HISTORY OF THE STAR-FISH. 
207 
good-sized star) and surrounded by calcareous plates, larger animals, which form the 
greater part of the star-fish bill of fare, are necessarily digested without being taken in 
through the mouth. The stomach therefore is turned inside out and, wrapping itself 
about the animal to be devoured, digests it where it lies, and is then withdrawn to 
its normal position within the body. It is safe to say that the stomach can be pro- 
truded for a distance equal to the length of the star-fish’s arm. 
The greater part of the animals upon which the star-fish prey are mollusks pro- 
tected by hard shells; for example, the sea-snails, mussels, quahogs, and oysters. How 
does the star get at the soft part of the mollusks? This question has given rise to a 
great deal of interesting, not to say amusing, speculation, especially with respect to the 
oyster. An old tradition in England and this country is to the effect that the star 
takes the oyster by suprise and puts an arm into its gaping shell ; then a fight ensues. 
Sometimes the oyster is victorious, while the star-fish retreats minus an arm, but often 
the oyster succumbs, since it can not live long with its shell open, and the star then 
devours its prey at leisure. There are two facts that are sufficient to disprove this 
theory. In the first place, the oyster is very sensitive and feels the slightest dis- 
turbance in the vicinity of the margin of the open shell. In the second place, the 
shell does not open wide enough to admit the arm of the star. Moreover, simple 
observation of the star-fish during the process of eating disproves the story. 
It is supposed by many that the star-fish injects a poisou into the shell which 
causes the latter to open. But the valves of the shell can be shut water tight and 
would exclude such a poison. I have taken away from the star-fish oysters, mussels, 
and drills which had already been opened, and placed them in an aquarium, where they 
soon recovered and behaved as though nothing had happened. Schiemeuz found the 
same to be true in the case of the quahog ( Venus ). 
Some have supposed that the star bores a hole through the shell of the victim, 
but the star has no boring apparatus, and the shells known to be opened by the star 
have no holes in them. 
It is a very common belief that an acid is secreted by the star, which dissolves the 
shell so that an entrance is effected. After a successful opening, however, the litmus 
paper shows no acid from the stomach of the star -fish, and the margin of the shells 
shows no trace of having been acted upon by an acid. A considerable quantity of 
acid would be required to sufficiently dissolve the shell of a medium-sized oyster, and 
this would undoubtedly dissolve, at the same time, the unprotected calcareous spines 
about the mouth of the star-fish itself. 
The most prevalent opinion is, perhaps, that the star chips away the thin edges 
of the shell until an entrance is gained to the soft parts. The broken edges of oyster 
shells which have been opened by the star seem at first to sustain this opinion. The 
process is thus described in a Providence newspaper: 
The star-fish seizes its prey by clasping its tentacles around the soft, fringy edge of the oyster, 
which it eats away until the soft oyster can be sucked from the oriiice, etc. 
Ingersoll, in an article on the oyster industry, after speaking of the alleged use 
of acid in opening the shell, says: 
Moreover, it seems unnecessary, since the appearance of every shell attacked at once suggests the 
breaking-down, chipping-off movement, which the star-fish might easily produce by seizing and 
suddenly pulling down with the suckers nearest the month, or by a contraction of the elastic opening 
of the stomach. At any rate, the thin edge of' the shell is broken away until an entrance is made 
which the oyster has no way of barricading. 
