ZOOLOGICAL SOCIETY BULLETIN 
19 
PILOT FISH (.NAUCRATES DUCTOR) 
A constant associate of the shark. 
Photograph by El win R. Sanborn. 
SHARK, SHARK-SUCKER AND 
PILOT-FISH 
By C. H. Townsend 
S INCE the Aquarium came into possession 
of the well-boat Seahorse two years ago, 
certain marine fishes of migratory habit 
which had previously been considered rare, be¬ 
came common in our collections. The fish ex¬ 
hibits increased not only in numbers of speci¬ 
mens, but in variety of species. Comparative 
rarities, such as shark-sucker, pilot-fish, file- 
fish, trigger-fish, pompano and mullet are now 
to be seen there regularly. 
One of the best exhibitions of fish life in the 
Aquarium today is a five foot sand shark ac¬ 
companied by its inevitable parasite, the shark- 
sucker, and followed at a safe distance by a 
small group of pilot-fishes. 
It is the destiny of the shark perpetually to 
tow through the seas the loafer, foreordained 
to be a hanger-on since the beginning of fish 
time. 
The shark-sucker does not insist that the 
shark alone furnish him free transportation, 
but is a stow-away on the porpoise, the whale 
and the sea turtle. Anglers report that it 
clings to the big tarpons caught in Florida 
waters and may be seen when the tarpon makes 
its great leaps. This may be done for the 
purpose of dislodging the sucker, as it has been 
seen to let go at such times and drop back into 
the water. It is not averse to clinging to the 
bottoms of boats. It was this habit which 
gained the fish the name of 
“ship-holder,” the ancients 
believing it to hold back 
vessels; and its name Eclie- 
neis has this meaning. 
Our large sand shark has 
been accompanied for six 
months by the Eclieneis , 
which has sliowm no inclina¬ 
tion at any time to attach 
itself to the other sand 
shark in the same tank. 
We have watched por¬ 
poises playing under the 
bow of a schooner with 
shark suckers firmly at¬ 
tached. The sucking disc 
on the top of the head, by 
which it clings, is longer 
than the head of the fish 
and has a surprising hold¬ 
ing power, as has been 
proved in the Aquarium. 
A large shark-sucker lowered partially into a 
pail of water, took hold of the side of the 
pail with its disc so firmly that when raised 
by the tail it lifted both bucket and water, a 
weight of twenty-four pounds. During the 
past two summers the Aquarium boat brought in 
sand sharks and shark suckers at various dates 
between J uly 7 and October 11, all taken iu 
Sandy Hook Bay. Many of the sharks and 
sea turtles entering the bay, must be accom¬ 
panied by shark-suckers and pilot-fishes that 
cannot escape capture when the former wander 
into the big pound nets. We do not get them 
elsewhere. 
We are not quite justified in referring to the 
shark-sucker as a parasite, when it is really a 
commensal—implying a living together. It 
does the shark no harm and may even be of 
service to it in destroying parasitic crustaceans 
which attach themselves to many kinds of 
fishes. We are not warranted in assuming that 
the shark has any concern about the welfare of 
the shark-sucker, since the latter is careful 
never to place himself in advance of the shark, 
but clings to back or belly, well out of harm’s 
way. When we placed pilot-fishes, which also 
accompany sharks, in the shark tank, they were 
evidently at a disadvantage in caring for them¬ 
selves and the larger shark managed to kill 
three of them. It is probable that the shark- 
sucker would fare no better if it swam about 
as freely as the pilots. We have noticed that 
it is careful to shift its position on the larger 
shark when the smaller shark swims too near 
for comfort. What a life “twixt the deil and 
