Transcript Jellyfishx

Jellyfish
Golda Gozum
M.L. Anderson, 2009
What is a Jellyfish?
• Jellyfish are invertebrate species of sea
dwelling animals that are so named due to
their gelatin-like bodies. Jellyfish are not fish.
Cnidarians
• The word Cnidarian comes from the Greek, “cnidos”
which means “nettle”. Nettles, or nematocysts, are
stinging cells, and all Cnidarians have them. These
are some of the oldest, largest and most poisonous
creatures on Earth.
Red striped sea nettle
Scyphozoa
• There are four major classes:
• Hydrozoa – Hydroids,
Siphonophores
• Scyphozoa – True Jellyfish
• Cubozoa – Box jellyfish
• Anthozoa – Sea anemones and
Corals (Discussed in a different
presentation)
Hydrozoa
Staurozoa
Cubozoa
Cambrian Period; 540 mya
• Ancient, simple animals.
• Fossil records date back
to the Precambrian Era,
550mya.
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There are about 10,000 species.
Scyphozoa with @ 200 species,
Staurozoa @ 50 species,
Cubozoa @ 20 species,
Hydrozoa @ 1000-1500 species.
Cnidarians
Jellyfish Features
Box Jellyfish
Purple striped Jellyfish
• A typical jellyfish body
is composed of the
bell, the oral arms or
feeding arms, and the
tentacles.
• There are some
species that do not
have tentacles.
• Jellyfish come in a big
variety of colors like
white, blue, pink,
yellow, green, purple,
red, orange, and
striped.
• The bright colors and
tell their enemies that
they are dangerous
fish.
Jellyfish Features
Red striped sea nettle
• Ancient, simple animals.
• Fossil records date back to the
Precambrian Era, 550mya.
• There are about 10,000 species.
• Size ranges from a few mm to over
30m.
• All are predators and carnivores.
• They spend their lives in sessile
polyp forms, as free-swimming
medusa, or both.
• As polyps the tentacles point up, as
medusa the tentacles point down.
• They have both asexual (polyps)
and sexual (medusa) reproduction.
Life Cycle
• Jellies go through several different body shapes in the course
of their life..
• Adult, free floating medusas produce eggs and sperm.
• Newly hatched larvae float in the currents until they find
somewhere to attach.
• After a short time living attached to a hard surface, the polyp
divides into many ephyrae, which peel off and float away.
• Ephyrae float and feed and grow until they are medusas, and
the cycle starts all over again.
Location
• Jellyfish live in oceans throughout the world.
• Few species inhabit saltwater lakes.
• Some jellyfish prefer warm, tropical waters
while other species prefer cold, arctic waters.
• Jellyfish live in many oceanic zones, from
shallow inshore waters near coastlines, to
open ocean.
• They survive at a variety of depths, some
species inhabit the top level of water while
others inhabit darker, deeper depths.
Scyphozoa – True Jellyfish
• No head, skeleton, or special organs for respiration
and excretion.
• Stings vary in potency – mild to very potent.
• Range in size from 12mm to 2m across.
• A group of jellies is a ‘smack’
• Alternates between sessile polyp and free-swimming
medusa.
Siphonophores
• It resembles a jellyfish but is actually a
colony of specialized individuals, such
as the deadly “Portuguese Man-ofWar”.
• Nutrients are shared through a
collective gut system.
• Other hydrozoans form
massive colonies that
resemble coral, but are
not, such as the highly
toxic “fire corals”.
• Hydrozoans alternate
between sessile polyp
and free-swimming
medusa stages.
Cubozoa – Box Jellyfish
• They look like basic jellies but
are box shaped.
• Tentacles are on each corner
of the box shaped bell
• They have well-developed
eyes
• They have a simple brain
• Unlike other drifting jellies, box
jellyfish are strong swimmers
• Also called sea wasps
• There are about 20 species in
tropical waters
• Some are highly toxic
They are responsible
for helping maintain
balance in the delicate
ecosystem of the
ocean.
Since jellyfish are a
kind of plankton, they
have a direct effect on
the food supply in the
deep sea.
Importance
• Jellyfish are
carnivorous.
• They eat mostly
zooplankton, smaller
fish and sometimes
other jellyfish.
• Bigger jellies eat
large crustaceans
like shrimp and
other sea animals.
• Jellyfish have an
incomplete digestive
system, meaning that the
same orifice is used for
both food intake and
waste expulsion.
They are often eaten by
sea turtles, sunfish, and
spadefish.
Crabs and other large
crustaceans also snack
on jellyfish, too.
In some Asian countries,
even people eat jellyfish.
Environmental
Concerns
• Seafloor habitats are
being destroyed by
overfishing, rising water
temperatures and
decreasing marine
biodiversity, and
reducing the ability of the
seas.
• This could make way for
increasing invasions of
jellyfish and microbes.
Jellyfish compete for
many of the same food
sources as fish, so fewer
fish in the seas means
more room for jellyfish.
Environmental Concerns
• Increasing numbers of fishermen nets are filling with
jellyfish, which slime, poison, and crush the intended catch.
Jellyfish are changing ecosystems, stinging beachgoers,
and causing millions of dollars worth of damage.
Fun
Facts
• The box jelly fish contains a venom which is the
strongest venom throughout the entire animal
kingdom.
• Lions Mane Jellyfish, largest known jellyfish.
• It can grow up to 7 feet and its tentacles can reach
up to 120 feet in length.
Fun
Facts
Moon Jellyfish
The Moon Jellyfish is the jellyfish that is usually
washed up on beaches during the summer high tides
and winds.
By the time the Moon jellyfish is washed up on the
beaches, the tentacles are gone and these jellyfish are
harmless.