[9] THE BOTTOM OF THE GULF STREAM. 10f)3 



that abound on these bottoms. Many fishes, like the "hake" {Phycis), 

 of which two species are conjinon here, ha\«o the habit of rooting in the 

 mud like pigs for their food, w^hich consists largely of Annelida and 

 other mud-dwelling creatures. Other fis^hes, those with sharp tails 

 especially, burrow actively into the mud or sand, tail first, and in all 

 l)robal)ility MacruruSj abundant in this region, has this habit. Several 

 species of eels and eel-like fishes are very abundant on these bottoms. 

 These are all burrowers. The "slim?-eel" or hag {Myxinc (jlutinosa) 

 was also taken in large numbers both in the trawl and in traps. Many 

 crabs and allied forms are active burrowers. Such creatures, by stir- 

 ring up the bottom sediments continually, would give the currents 

 a «hance to carry away the finer and lighter materials, leaving the 

 coarser behind. 



In many localities in the region under consideration there are great 

 quantities of dead shells, both broken and entire. A small i)roportion 

 of the bivalvOvS have been drilled by carnivorous gastroj)ods, but there 

 are large numbers that show no injury whatever. There is no doubt 

 in my mind but that these have for the most part served as food for the 

 star-fishes and large Actinice, so abundant on these grounds, and from 

 which I have often taken entire shells ot many kinds, including ptero- 

 pods. Many fishes, like the cod, haddock, hake, etc., have the habit of 

 swallowing shells entire, and after digesting the contents, they disgorge 

 the uninjured shells, and such fishes abound here. 



The mollusks represented by the numerous broken shells hitve probably 

 been preyed u|)on by thu crabs and other Crustacea, having claws strong 

 enough to crack the shells. The large species of Cancer and Geryon, and 

 the larger Paguroids, abundant in this region, have strength sulficient 

 to break most of the bivalve sUells. Although I have often seen such 

 Crustacea break open bivalves for food, I am well aware that they also 

 feed on other things.* Many fishes that feed on mollusca break the 

 shells before swallowing tliem, so that both fishes and crabs have doubt- 

 less liel[)ed to accumulate the broken shells that are very often scat- 

 tered abundantly over the bottom, both in deep and in shallow water. 

 Such accumulations of shells would soon become far more extensive if 

 they were not attacked by boring sponges and annelids. Certain com- 

 mon sponges belonging to the genus Cliona very rapidly i^erforate the 

 hardest shells in every direction, making irregular galleries, and finally 

 utterly destroy them. In our shallower waters the most destructive 

 species is G. sulphiirea (Desor), which burrows in shells and limestone 



*I have observed that when in aquaria, mauy different species of the larger crus- 

 tiioea, such as the crabs, Libinia emarginatd, Cancer irroratus, Panopens Sayi, Carciiias 

 nuenas, Platijonicm occtUaius ; the hermit-crabs, Eupagurus polKcaris, E. longicarpus, a»d 

 Catapagurus socialis ; the shrimp, rcd(Pmonetes vulgaris and Virhius zostericola ; and imw- 

 lus polyphemus, are all extravagantly fond of the masses of diatoms and other line algse, 

 intermingled with copeopods, etc., which we often collect in our surface-nets. When 

 a mass of such materials is thrown into an aqiiarium containing these Crustacea they 

 seize and devour it with great avidity. 



