Animasi dan bahan ajar Biologi SMA Cnidaria

Phylum Cnidaria or Coelenterata
Jellyfish, anemones, corals

The Basics
 Two tissue layers - an outer epidermis and
an inner gastroderm
 Nerve net with stinging capsules called
nematocysts
 Radial symmetry with 2 body types - a
polyp and/or medusa

The coral animal may
live as a free-floating
polyp or build colonies
into reefs. Not all
corals build reefs.

Stony Coral
 Hermatypic or reef builders
 Polyp grows in 6 parts to form a body of
calcium carbonate

 Brain coral and staghorn coral

Soft Coral

 Polyps with 8 tentacles
 While part of the reef,
they do not build reefs
because their bodies
are a soft keratin.
 Sea fans and
gorgonians

Hydrocoral
 False corals resemble the anemone
 contain powerful nematocysts that cause
skin irritation
 Fire coral

Some cnidarians
exist as

individuals and
others live as
colonies like the
Portuguese manof-war.

It has a gas filled float and
individuals that function like
specialized organs. Some are
carnivores with digestion in food
vacuoles.

Cnidarians
Class varieties

Hydrozoans - Class Hydrozoa
 Feathery or Bushy colonies of tiny polyps
 Polyps may be specialized
 Attach to pilings, shells, seaweed, etc.
 Siphonophores - hydrozoans that form
drifting colonies (Portugues man of war)

Scyphozoans - Class Scyphozoa
 Larger jellyfish
 Bell of some medusae may reach 2 m.
 Some are the most dangerous in the world

Anthozoans - Class Anthozoa
 Solitary or colonial polyps that lack a
medusa stage.
 Sea anemones
 Stony corals and sea fans

Textbook readings
The case of the killer Cnidarians