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About Jellyfish Anatomy,
About Jellyfish: Jellyfish have Survived for 650 million Years
phylum Cnidaria. This phylum is
divided into definitive classes which include all anemones, corals,
and what is commonly referred to as true jellyfish. Anthozoa contains
and anemones. Hydrozoa includes the Portuguese Man o`War which contrary
popular belief is not an actual jellyfish but a massive colony of
The class Cubozoa contains box jellies, the deadliest creatures on
jellyfish belong to the class Scyphozoa which includes over 200 species.
exist in every ocean on the planet. They cover the
entire spectrum of oceanic depths from shallow estuaries and lagoons to
deepest, largely unexplored regions of the aquatic domain. The most
geographically diverse and easily recognizable of these creatures is
the moon jellyfish (Aurelia) or common jellyfish which contains twenty
that are so identical morphologically that it takes DNA testing to
one form another. From a non-scientific standpoint, moon jellyfish
might as well
|Despite the fact that
jellyfish are one of the most prolific life forms on the planet,
until recently it was thought impossible to keep jellyfish
alive in captivity. In fact, the world's first public
jellyfish exhibit opened at the Monterey Bay
Aquarium just a little over twenty years ago.
The technological advancements needed to keep these delicate creatures
alive and healthy in captivity paved the way for the newest segment of
the aquarium industry, the jellyfish fish tank aquarium.
This specialized branch of the home aquarium industry is
still in its infancy. A decade ago there was no
such thing as a home jellyfish tank. It has just been in the
past two years that this new trend in aquarium home ownership has
produced an affordable desktop jellyfish aquarium. For
more information go to Jellyfish Aquariums.
Check Out the Newest
Desktop Jellyfish Aquarium on the Market
About Jellyfish: Jellyfish Anatomy
can best be described as a sac
within a sac. They are composed of approximately 95% water, 3% salt and
protein. They have no eyes, no brains, and no supporting skeletal
yet are one on the oldest multi-cellular creatures known to man. They
long before the first dinosaurs roamed the Earth and will almost
still be here long after the human race has vanished. Without a brain,
jellyfish have managed to survive three planetary wide extinctions:
This alone bears
testimony to their long term survivability as a life form.
Jellyfish are one
simplest multi-cellular organisms in existence. They
are most accurately described as gelatinous zooplankton. The actual
jellyfish is a universal misnomer. Jellyfish are, of course,
not fish. Jelly
refers to the gelatinous substance that accounts for most of the mass
in a jellyfish’s
umbrella or bell. This jelly (mesoglea) is surrounded by two layers of
epithelial cells. The top layer forms the upper portion of the
bottom layer forms the subumbrella or underbelly of the bell.
do not have
specialized digestive, respiratory or circulatory systems.
In fact, they don’t even have blood cells. Oxygen is absorbed
diffusion through their thin outer membranes. A second membrane within
jellyfish contains a gastrodermal lining which forms a gastrovascular
This primitive cavity functions in place of a digestive system.
absorbed and distributed throughout the body. Jellyfish either have a
mouth or multiple mouth openings positioned on oral arms that function
intake of nutrients and expulsion of waste products.
species in the order
Rhizostomae have a symbiotic
relationship with algae colonies living inside them. These jellyfish
host body for the algae. In exchange, the algae provide carbon rich
for the jellyfish. In addition to essential nutrients, the
photosynthetic process produces oxygen to help support metabolic
functions in poorly oxygenated environments.
Rhizostomae Jellyfish in Action
Jellyfish do not
brains or a central nervous system. Instead they have
a rudimentary neural network called a nerve
net running throughout their
epidermal membrane. They have no eyes,
although many have ocelli. Ocelli are basic light sensory organs. They
sophisticated enough to form visual images but can distinguish light
This gives them the ability to sense a foreign object so they can
around it. Aside from distinguishing between light and darkness in some
species, a jellyfish’s awareness of external environmental
factors is limited
to being able to determine between up and down, and tactile impulses.
sense when they have come in contact with another object.
Jellyfish also lack any
semblance of an advanced skeletal system. They have
what is called a hydrostatic skeleton that provides structural
allows for limited mobility. Hydroskeletons are common in many lower
forms, specifically cold blooded and soft bodied organisms. A
consists of fluid or gelatinous filled cavity called a coelom.
typically surrounded by muscular tissue or muscle-like membranes. As
tissue contract or expand the pressure of the fluid in the coelom is
This change in fluid pressure is what allows jellyfish to change shape
achieve locomotion. Most jellyfish are poor swimmers. They spend the
majority of their adult lives drifting haplessly on the ocean currents.
jellies, however, are quite good swimmers. Sea nettles are such
swimmers that they spend most of their time swimming, quite frequently
against prevailing currents. This is why they appear to be
swimming upside down.
Sea Nettle: Pure
Poetry in Motion
About Jellyfish: LifeCycle & Reproduction
fish have two distinctive phases to their lifecycle. The
first is the polypoid or polyp stage. The second is the medusa or adult
These are the free swimming jellyfish to which people are accustomed
typically occurs both sexually and
asexually. The initial stage of a jellyfish’s life cycle
begins with sexual
reproduction. A male jellyfish releases sperm from its mouth into the
of these sperm make their way into the mouth of the female jellyfish
eggs are stored. After initial fertilization, embryonic deployment
inside the female’s mouth or in brood pouches inside her oral
arms depending on
the specific species involved. Eventually, free-swimming larvae are
into the water. These larvae sink to the ocean floor and
themselves to stationary objects. At this point they develop into
polyps. They will remain firmly anchored until nature signals that the
stage of their reproductive cycle is about to commence.
reproduction involves strobilation of the existing
polyps. Stobilation simply means that the polyps segment and re-segment
a colony of polyps much like a single cell organism divides to form a
unique organism. Most
strobilate in the winter months. They will remain attached together as
sessile colony of polyps until spring signals the next phase of their
lifecycle. The chart above pictures the complete jellyfish life
the warming of the water, this colony of polyps breaks
apart into individual, free-swimming medusa. It is this medusa, or
of the jellyfish’s life that beach goers come into contact
with. Many species
of jellyfish instinctively seek shallow water to initiate the sexual
their reproductive cycle. It is in this stage of the reproduction
human interaction is most likely to occur. Some species of adult
in massive swarms called blooms. It is not uncommon for a bloom to
100,000 adult jellyfish.
Jellyfish are cyclic in
nature. In the wild, most
jellyfish’s lifecycle takes one calendar year to complete.
captivity are not bound by the mandates of nature. They have been
documented to live
for over 10 years in public aquariums.
2009 scientists discovered a previously unknown species
of jellyfish, Turritopsis
species of jellyfish is unique in that it has the ability to reverse
and revert from an adult to a juvenile thus cheating the seasonal
dictates of a
jellyfish’s lifecycle. This is the only animal known in
creation to have the
About Jellyfish: Global Jellyfish Invasion
In recent decades
jellyfish bloom density and populations have increased
dramatically. Scientists point to the rise of ocean temperatures (due
warming) and over fishing as possible catalysts behind these population
explosions. While warmer water temperatures are conducive to jellyfish
morphing into adult medusa, there is no empirical data to support these
speculations. In truth, there is simply not enough documentation
existing on long-term
jellyfish population patterns to offer anything more than scientific
speculation. Case in point: The sudden and devastating rise in the
populations that plagued the Midwestern United States in 1874. We have
of knowing whether this was a cyclic rise in population or was caused
intervention with nature. Periodic locust infestation could have taken
for centuries in the Midwest. American settlers were
just not around to document the devastation.
thing is certain: The rise in jellyfish populations has cost untold
millions in revenue loss to the tourism industry. Australia,
America, and countries
throughout the Mediterranean coastline have
all experienced significant rises in jellyfish populations in recent
decades. 2005 Newport
1,400 people had to be treated for jellyfish stings in a single day.
Brava Spain 2006: Over 19,000 beach goers were treated for jellyfish
beaches have experienced jellyfish concentrations of over 10 jellyfish
square meter in recent years. The beach resorts in Mexico
have had to be closed on more than one occasion
due to jellyfish infestation.
deadly box jellyfish populations have also risen dramatically. Box
have migrated all the way to the shores of Hawaii.
Hawaiian beaches have had to start posting the same “Deadly
signs that Australians have learned to accept as a way of live in the
jellyfish breeding season.
jellies and their smallest members the Irukandji jellyfish inundate the
coasts of Northern
Australia from November
An adult box jellyfish contains enough venom to kill 60 people. They
grown adult in as little as 2 minutes. Sting victims frequently go
anaphylactic shock if anti-venom is not promptly administered. Netted
provided for Australian beach goers to keep them out of harms way.
jellyfish present an entirely different problem in regards to human
interaction. These jellyfish are no larger than your finger nail and
completely transparent. For all intents and purposes they jellyfish are
invisible to beach goers. Nets are completely ineffective in isolating
from the public. While their venom is not as fast acting as that of
larger cousins, there is no anti-venom currently available for
Syndrome. Doctors can only treat the sting victim’s symptoms
and hope the
patient survives the ordeal. If their presence is detected, the beaches
Tourism is not the only
industry to suffer in light of the
global jellyfish explosion. On October 23,
2008 alarms began to sound
the Diablo Canyon Nuclear power
plant in San
Luis Obispo County.
Water pressure readings from the plants cooling systems were
explanation. Underwater scuba teams surveyed the plant’s
cooling intake system and
determined that 100s of moon jellyfish had completely jammed the intake
Officials had no choice but to power down the plant. A bloom of
inauctious jelly fish had succeeded in doing what years of
protestors had failed to accomplish. Jellyfish
have also clogged desalination plants and ship intakes.
hardest hit industry in recent years is the commercial
fishing industry. Jellyfish blooms have clogged and broken nets,
catches and threatened to shut
down fishing operations completely in
more than one
region of the world. The giant Nomura’s jellyfish (Nemopilema nomurai)
has even capsized fishing boats off the
coast of Japan.
Attacks: The Truth about Jellyfish Stings
to popular belief, no jellyfish has ever actually
attacked a human being. Jellyfish are, in fact, one of the most fragile
creatures in creation. If not for their ability to sting, they would be
defenseless against predators and left to starve from malnutrition. The
jellyfish’s nematocysts (stinging cells) are
nature’s way of compensating for
their delicate constitution. A jellyfish’s
triggered by touch.
This is a strictly autonomic response to physical contact.
jellyfish are the most lethal creatures on the face of the Earth. But
not all jellyfish stings are deadly. There are almost 30,000 species of
jellyfish worldwide. The sting of many of these species is
human beings. Some jellyfish nematocysts do not even generate enough
pressure to penetrate human skin. Still others are no more aggravating
bee sting to the average person. They will produce no more than
irritation and a minor skin rash. This is not to say that a jellyfish
should be taken lightly. Just like a bee sting, each individual reacts
differently to the introduction of invasive toxins to their system. A
for most people is no more than a minor annoyance. To others an adverse
allergic reaction to bee venom means an emergency trip to the hospital.
But even the
jellyfish venom may prove beneficial to mankind.
Modern science has already found one aspect of a particular species of
extremely helpful in the field of biological research. Crystal
jellyfish (Aequorea Victoria)
contain a naturally occurring biofluorescent gene called Green
(GFP). Scientists have been able to isolate and synthesize this gene.
almost single-handedly revolutionized cellular biology. It has made it
for researchers to see inside living cells and understand how they work
first time. It is hoped that the paralyzing aspects of jellyfish venom
to unlocking the key to the cardiovascular system.
is one place on the planet where tourist can swim worry free while
surrounded by millions of jellyfish. It is Clear
on the island
of Eil Malk
Eli Malk is one of a series of volcanic outcroppings that make up the Rock
stratified marine lakes are exceedingly rare, the Rock
contain over 70 of them. Clear
Lake (also known as Jellyfish Lake or
Lake Palau) has been isolated from predators for over 1,2000 years even
it is still connected to the ocean. It is connected through a series of
and fissures in ancient limestone reefs that
| date back
to the Miocene Era. This
lake is teaming with millions of golden jellyfish (Mastigias
an algae dependent jellyfish that has evolved for thousand of years in
rich waters. Between their symbiotic relationships, abundance of
nutrients and total lack of predators, the golden jellyfish has
into the most benign jellyfish on the face of the planet. Golden
longer have the ability to sting.