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Recently the Caribbean Carousel
went for an adventurous day at Cumac River water falls in the Northern
Range mountains, Trinidad.
While we were there we had alot of fun after a one
hour hike through the forest and up the river.
When we got to the Falls after an
enjoyable hike through the forest it was exciting to see the brilliant
white waters cascading down the rocky slope crashing into the clear, blue
green waters of the pond below, surrounded by a carpet of tropical ferns.
It sure was an amazing sight to behold
But our story today is about the Crayfish in the rivers around Trinidad.
Crayfish are marvelous organisms.
Crayfish are crustaceans. Their appearance is bizarre—they are
festooned with a bewildering array of walking legs, pincers, and other
appendages for eating, feeling, and attending to other crayfish business.
Equipped with thousands of sensory bristles, some sensitive to chemicals
and the others to touch, crayfish can smell, feel, and hear acutely, even
though they are completely covered in a hard shell. They are aquatic, but
can survive fairly extended sojourns on dry land as long as their gills
remain moist.
More than 1 crayfish? I guess the plural of crayfish is
crayfish, and as for fish, when you talk about more than one species it
would be crayfishes!!
HABITAT
Where do they live?
Crayfish
probably inhabit all aquatic environments in the Caribbean. They can be
found in lakes, rivers, streams, marshes and ponds. Wherever there is a
permanent body of water that is deep enough, you may find crayfish.
The
one habitat requirement that the crayfish seems to have is the need for
shelter in the form of rocks, logs or thick vegetation in which to hide
from predators during the day time.
Crayfish like it dark and cool, and
during much of the daylight they will be found alone, withdrawn under a
rock or a clump of vegetation, waiting for dark, at which time they come
out to forage for food.
HABITS
Crayfish are most active
at night. They leave the protection of the rocks or other cover to forage
in the dark, no doubt aided by their long, sensitive antennae.
They can
even crawl up onto land next to water to go from pool to pool in search of
food or to forage along the shore.
The location of their gills under the
carapace means that they stay moist for some time even when the crayfish
is out of the water. This and the crayfish's ability to tolerate low
oxygen levels allows them to venture from the water for short periods.
If
encountered on land by a predator, they adopt a
defensive stance with claws at the ready.
WHAT DO THE EAT?
Crayfish are omnivorous, eating just about
anything they can find or catch, dead or alive.
Large food is held and
torn to pieces in the large pincers and conveyed to the mouth by the
smaller specialized legs near the head.
That's what crayfish mostly do:
loaf all day and look for food all night.
Crayfish eat some aquatic
plants as well as invertebrates, such as snails and insects, and tadpoles
and small fish.
They are probably best described as "opportunistic
omnivores", they eat whatever they can get!.
While they can catch some
quick moving prey like tadpoles or fish, they probably get a lot of their
food by scavenging dead animals.
Crayfish As Food
What eats crayfish?
Fish are probably
the main consumers of crayfish. But turtles, herons, cranes and lots of
other animals will chow down on crayfish when they can catch them.
Crayfish are an important part of the aquatic food chain. They are also an
important part of the human food chain!
In many parts of the world
crayfish are a delicacy.
MOLTING.
Think about the problem of living inside a suit of ARMOR.
Crayfish can't grow unless the shell (comprising the carapace, or main
body shell, tail shell, and leg shells) can be removed. And this is
exactly what crayfish do.
Periodically the
crayfish slides out of its old, hard shell in a process called molting. Like all arthropods (animals with a
hard exoskeleton and jointed legs: crustaceans, insects, arachnids, etc.)
they must shed their hard shell-like skin in order to grow. For several
days after moulting, crayfish stay in seclusion until their new skin
hardens enough to protect them from predators.
The "naked" crayfish that emerges is actually covered in a complete and
perfect shell, but it is soft and flexible, allowing the crayfish to
expand and grow.
After a day or so the new shell will become hard, again
affording the animal the protection of an armored exterior.
In preparation
for molting the crayfish withdraws most of the calcium from its shell, and
stores it in two white "tablets"in the sides of its head..
Calcium is a
major hardener in the crayfish shell, as it is in strong human bones and
teeth. With this precious supply of calcium the new shell can harden in a
matter of hours instead of days or weeks.
REPRODUCTION
But there are times in a crayfish's life when
the routine is broken. Males and females, spurred on by messages
communicated to each other, join periodically for mating, especially in
the spring. Males can be told from females by the generally larger pincers
and narrower tails, but these characteristics are not absolute. To tell
for sure, you must pick them up and look underneath. Males have two pairs
of modified swimmerets (the small leglike appendages under the tail) that
are white-tipped and lay between the last pair of walking legs. The
females have longer, softer-looking swimmerets (for holding the eggs) and
a little white pore centered between the walking legs. Some time after
mating the female lays about 200 eggs, which she carries in a mass under
her tail in a large ball resembling a raspberry. In fact, the females
are said to be "in berry" while they are carrying their egg masses..
After several weeks the eggs hatch, and a hoard of minute,
perfectly formed, ravenous baby crayfish emerge. At first they continue to
ride along under the female's tail, eating tiny waterborne bits of food,
but soon they leave this security and head out on their own. During these
early days many are eaten by fish, insects, and other crayfish, but some
always survive to fulfill their destiny.
Crayfish don't live very long. The males
usually die after mating when they are about 2 years old. The females die
after their young hatch, also at about 2 years of age. Crayfish
occasionally live longer, but it's thought that none survive beyond their
4th year.
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