The Outline of Science, Vol. 1 (of 4): A Plain Story Simply ToldThomson, J. Arthur (John Arthur)
Science
The Outline of Science, Vol. 1 (of 4): A Plain Story Simply Told
Thomson, J. Arthur (John Arthur)
Science
In another part of this book there is a discussion of camouflaging and
protective resemblance; how abundantly these are illustrated on the
shore! But there are other "shifts for a living." Some of the
sand-hoppers and their relatives illustrate the puzzling phenomenon of
"feigning death," becoming suddenly so motionless that they escape the
eyes of their enemies. Cuttlefishes, by discharging sepia from their
ink-bags, are able to throw dust in the eyes of their enemies. Some
undisguised shore-animals, e.g. crabs, are adepts in a hide-and-seek
game; some fishes, like the butterfish or gunnel, escape between stones
where there seemed no opening and are almost uncatchable in their
slipperiness. Subtlest of all, perhaps, is the habit some hermit-crabs
have of entering into mutually beneficial partnership (commensalism)
with sea-anemones, which mask their bearers and also serve as mounted
batteries, getting transport as their reward and likewise crumbs from
the frequently spread table. But enough has been said to show that the
shore-haunt exhibits an extraordinary variety of shifts for a living.
Parental Care on the Shore
According to Darwin, the struggle for existence, as a big fact in the
economy of Animate Nature, includes not only competition but all the
endeavours which secure the welfare of the offspring, and give them a
good send-off in life. So it is without a jolt that we pass from
struggle for food and foothold to parental care. The marine leech called
Pontobdella, an interesting greenish warty creature fond of fixing
itself to skate, places its egg-cocoons in the empty shell of a bivalve
mollusc, and guards them for weeks, removing any mud that might injure
their development. We have seen a British starfish with its fully-formed
young ones creeping about on its body, though the usual mode of
development for shore starfishes is that the young ones pass through a
free-swimming larval period in the open water. The father sea-spider
carries about the eggs attached to two of his limbs; the father
sea-horse puts his mate's eggs into his breast pocket and carries them
there in safety until they are hatched; the father stickleback of the
shore-pools makes a seaweed nest and guards the eggs which his wives are
induced to lay there; the father lumpsucker mounts guard over the bunch
of pinkish eggs which his mate has laid in a nook of a rocky shore-pool,
and drives off intruders with zest. He also aerates the developing eggs
by frequent paddling with his pectoral fins and tail, as the Scots name
Cock-paidle probably suggests. It is interesting that the salient
examples of parental care in the shore-haunt are mostly on the male
parent's side. But there is maternal virtue as well.
[Illustration: TEN-ARMED CUTTLEFISH OR SQUID IN THE ACT OF CAPTURING A
FISH
Public-domain text, read in full here on John Shaqi.
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