_
zoo
THE SEAS '
,
heating of the tail of the occupant, water is drawn in on the
upper side of the house through a pair of openings guarded
by a ne network and the extremely ne particles still
remaining in suspension are collected by a very complicated
sieve within the house.
The food is then drawn into the
month of the animal,again by the aid of cilia, while'the
strained
water
passes
out.
The
house
soon
becomes
useless on account of accumulations of particles which,
effectively clog it, and it is then abandoned by the animal——
after perhaps being in use for only a few hours—and a new
one in all its intricate detail constructed in half an hour
or
so!
Other members of the plankton which feed eXclusively by means of cilia include some of the delicate
Pteropods or "‘ sea butteries.”
_
Many or the smaller crustaceans have feathery limbs
for collecting nely—divided food.
The common barnacles
(Plate—78) are provided with six pairs of delicate limbs
fringed, with ne 'bristles’; which are alternatively shot out
.
‘
’
froin‘ the shell and —withdrawn, sweeping thrOughthe'water
like a casting net during the latter phase.
The process can
easily be observed by placing acorh—barnacles collected from
the rocks in a basin of sea
and cannot fail to ”be
admired for the grace and precision of the movements.
The_barr‘1aole literally
“
kickS its food into its _mouth.”
Many of the smaller planktonic crustacea, such as copepods,
create by the movement of their swimming legs currents
.
in the water all around” them, in which particles are drawn
in between the limbs and then forward along the under side
-
of the body, where the water is ltered and. the particles so «
collected pushed into‘ the mouth.
Some of them feed
.
exclusively
diatoms, others on smaller copepods, and
_
others again on a mixture of the two.
.
,
.
The small sea gherkins (such as Cucumaa and Thyone)
.
.
which live_in holes and cracks in the rocks and;have a ring
'