2. WHAT ARE THEY?
Jellyfish or jellies are the major non-polyp form of
individuals of the phylum Cnidaria.
They are classified as free-swimming marine
animals consisting of a gelatinous umbrella-shaped
bell and trailing tentacles.
The bell can pulsate for locomotion, while stinging
tentacles can be used to capture prey.
3. WHAT DO THEY EAT?
Jellyfish normally eats whatever their long tentacles
catch while drifting in the ocean currents. A few
species of jellyfish like the box jellyfish are good
swimmers and chase their prey. The main food
sources of jellyfish are smaller fishes, eggs and
larvae of sea creatures and zooplankton. The larger
species of jellyfish eat crustaceans and other
jellyfish.
4. FACTS
The same opening under the body that serves as
its mouth is used for releasing excreta from the
body. The food entering the opening is digested in
the cavity attached to it. The waste matter
generated is expelled through the same opening.
Jellyfish is carnivorous and ravenous eaters. The
mouth of the jellyfish is located underneath the bell-
shaped body. Its simple digestive system consists
of a gastro vascular cavity attached to the oral
opening, which does the function of the stomach.
5. The tentacles are the main devices to catch prey for
jellyfish. These tentacles have thousands of cnidocytes
with stinging capsules or nematocysts containing
venom. Even though these creatures are brainless, their
nervous system is highly developed. When the tentacles
touch a potential prey, the cnidocytes are activated
immediately. They shoot nematocysts at the prey, which
attach itself to the skin of the prey. The venom present in
these nematocysts is released, which in turn stuns the
prey.
The shocked prey is caught by the arms surrounding the
oral opening and brought to the mouth. The food is
digested immediately in the chamber attached to the
opening and nutrients absorbed by the body. The waste
is discharged through the same opening.
6. Many species of jellyfish are passive hunters and
wait for their prey to come to them. They have
sticky tentacles and drift along the currents waiting
for a prey to get trapped in the tentacles. They eat
mostly zooplankton, eggs and larvae of other
marine creatures and crustaceans.
Some species of jellyfish are aggressive hunters
and they are equipped with potent venom in their
tentacles. This venom when ingested in the prey
either paralyzes or kills it. This group of jellyfish
preys on smaller fishes, crustaceans and even
other jellyfishes. Some jellyfish is known to eat
other jellies as large as themselves.
