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The
STRANGE
L ife
The (unknown to some) life of the jellyfish
~By~
Parker
Respect that fact!!!
Enjoy!
Introduction
What are jellyfish? They are animals, of course. To some,
though, it doesn’t seem that way, and it’s easy to understand why.
Their natural yet almost non-understandable bodies seem to set
them apart from all other animals. Despite all this, they are in fact
entirely natural. Not only are they thriving, but they also have an
effective lifestyle. This style may only seem effective to some by
hearing the rest of my report, or getting information from another
source. But in the meantime, you are about to hear the rest of my
report. Once it’s over, you will (most likely) understand their
different, complicated life.
Habitat
Jellyfish live in oceans all over the world. Different kinds
live in different areas, which are mostly in some part of the open
ocean. The largest can grow up to 6 feet wide and 117 feet long
(which is just a little longer than Park’s field) and is found in cold,
northern waters. Other kinds live 3,300 feet beneath the sea in the
middle of the Atlantic Ocean! They have been found swimming
around coral reefs if they wander (or float) away from where
they’re normally found. They may be stranded on beaches, where
they melt into a puddle of gel, if they’re pushed even farther than
the reef. Species have most likely adapted to where they live, and
also to withstand the conditions of heat or cold in the water. Even
if they ventured into an unfamiliar place, they’re pretty much
geared up for anything except predators. This may be a hint to how
they have survived for millions of years.
Diet/Hunting
All jellyfish hunt. They almost all have stingers- or
nematocysts- that will fire barbed “harpoons” filled with poison
when the sense cells on them detect movement. This is the method
that most jellyfish use, although there are a few that differ. Two of
the more interesting methods are used by the Moon Jelly and the
Cabbage Blebs. They use methods different than the normal jelly
in many ways. They may only use their stingers for protection. The
Moon Jelly eats plankton, like most other smaller jellyfish do
(including the Cabbage Blebs). The way it catches these
impossibly small plants/ animals is by beating small hairs near its
mouth very, very fast. This causes a rushing current of water to
flow past its mouth. The hairs push the water into the mouth,
where it is filtered to remove the edible plankton, and send out the
excess water. This is a helpful method because water is always
there, plankton is always in the water, and whenever it needs food,
it’s always there!
The Cabbage Bleb’s method is similar, but not exactly the
same. It also eats plankton, and filters the water, like the Moon
Jelly. The only difference is that it has very small tentacles around
its mouth, which act like the hairs on a Moon Jelly in the same way
it uses them to send water past the mouth, but theses tentacles filter
the water in a way people cannot quite understand. This method is
helpful in the same way as the Moon jelly’s method, in a way.
Aside from the jellyfish that catch smaller prey, Jellyfish that catch
larger prey usually have long, semi- muscular tentacles (as long as
40 feet) to get their fish. They can reach for prey far down into the
abyss, and because the tentacles are muscular they can curl them
up to their mouth so they can actually eat them.
Although this is only a small selection of hunting methods,
only a few other jellyfish have extremely different methods as the
Cabbage Bleb and Moon Jelly, but until more are discovered, it’s
mostly the same.
The Jelly Body
Bodies. All animals have very complex bodies. On land, airbreathing animals have generally similar bodies. In the ocean,
though, there are strange and unnatural bodies, especially deep-sea
creatures. Most of the strangest bodies are a result of adaptation,
and are actually perfect for the temperatures and other conditions
that they live in. The jellyfish’s body has been given millions of
year to adapt to wherever that species lives. Strangely enough,
without a heart, brain or self-realization, their bodies are almost
perfect. Most people don’t realize that the dome shaped body, for
starters, is at all helpful when in fact it is. This is hard to believe
because their strange dome shaped “head” is very irregular and
different than any other creatures. Actually all jellyfish have a
dome shaped body and it is vital because it is not only a mouth but
also a “propeller” (see ‘locomotion’ for how) in the sense that it
moves the rest of the body forward. It is made up of two layers of
skin. The first layer is covered with sense cells. These can detect
light, gravity, and movement in the water. The jellyfish can sense
if a predator or mate is nearby with these cells. The first layer is
bound together with the other skin layer by a binding of nerves and
muscles. These will help with locomotion.
The mouth is in the center of the body, and the food is
brought up to it with the long, muscular tentacles hanging around
the center of the dome. Once the food enters the mouth the second
layer of skin digests it. It is unknown how the skin acts like a
stomach. These stingers can grow up to 40 feet if the species is
known for that. They are made to curl up to the mouth so they can
actually eat the food they catch. The food is hoisted up to the
mouth of a creature with one of the strangest bodies on earth that is
known so far.
Locomotion
Moving around. All animals do it. Whether it’s to escape
from predators or find a potential mate, so do jellyfish. Although it
seems impossible with their creepy body and dragging tentacles,
they can. Here’s how: the muscles and nerves in between the skins
open and close their “umbrella” of a body. These muscles cannot
pull it closed, but its jelly body is made out of gel, of course, and
when the nerves pull it open it bounces back into its shape. This
sends a jet of water to send it forward. Most jellyfish get around
like this, but there are a few exceptions. The Portuguese man-ofwar is one, for instance. And truly, this creature is not a true
jellyfish. It is made up of thousands of tiny polyps that stick
together to make a giant “bell” of a body. It is pushed around by
the wind like a sailboat on the water. This may seem like a strange
and unhelpful maneuver, but not as weird as the Cassiopea, or
upside-down jelly. All it does is crawl around on the sand on the
bottom of the ocean using its muscular flat dome. It is also able to
lift off the bottom by curling up its body in a sort of fan-like way.
It will float to find food (plankton). The Cassiopea has a VERY
un-animal-like way of moving. So does the man-of-war. They all
do, or so we hope. Then they would lose what makes these
fascinating things less fascinating.
Reproduction/ Life Cycle
There are a lot of jellyfish. There have been for millions and
millions of years. In order for them to stay, there has to be
reproduction as well as a safe life cycle. And they do have one. It
all starts with many different gatherings (or shoals) of jellies come
up to, or closer to, the surface. Different shoals are gatherings of
different species. Once all together, the males release sperm into
the water. Any available female soaks it up through her mouth.
Once inside her, the sperm fertilizes 1,000’s- not just one- of the
eggs. They give birth to this many offspring because of the fact
that predators may eat some without noticing. These eggs stay
inside the female for a short while. They will hatch inside her
when fully ready, then float out of the females mouth. They are
now free to roam alone, and to begin their life cycle.
In the first stage of growth, they stick themselves to rocks
until they have grown to be big enough to swim. When they are
ready, they disconnect and officially enter their polyp stage. In this
stage they look like a long, swimming sea anemone. After a week
in this stage, its body splits into discs called dishes. The excess
dishes all become other polyps and go into the medusa stage by
themselves. In the medusa stage they start to look like a small,
deformed jelly. They are now hunting and swimming. Using the
food, the medusae will start to change over time into real jellyfish,
looking like a person normally sees them. Of course, in a
jellyfish’s case, normal is strangely interesting.
Predators
Although jellyfish are powerful hunters and very poisonous,
they are not the big fish that eats the little fish, or in other words,
they are not at the top of the food chain. In fact, the leatherback
turtle eats almost nothing but jellyfish, even stinging ones. Certain
kinds have many predators, including the sea slug. First, it covers
itself in sting-proof mucus and bites the jellyfish’s stinging
tentacles off! It will store them on its own back for protection. This
will leave the jellyfish vulnerable to attack without any defense.
They can be attacked by crabs (crabs have been seen ripping apart
jellyfishes on the sea floor) or sea turtles. Different jellyfish
species may have many, many predators. Certain species are even
captured by humans. In China, non- stinging jellies are captured
with nets and brought ashore. They are cut into strips and soaked
in water for twelve hours. Once ready, they are served in salads or
served alone with soy sauce and vinegar. Although jellyfish salad
is a treat to some, they kill thousands of jellyfish to make it. This
makes humans a dangerous predator. All of their predators are
dangerous, but nonetheless jellyfish are a strategic predator too.
They can still survive. Mostly.
Conclusion
I hope you have learned more about jellyfish, and noticed
how lively and living they are. Even though this report has a lot of
facts about their strange and complicated life, there is still much
more to learn. I hope you will pass this information on to other
people, so they can learn more about jellyfish as well as understand
them more.