Phylum Cnidarians

Jellyfish, hydra, and sea anemones

Characters of Cnidarians

Sort bodies that exhibit radial symmetry, 2 germ layers

Cnidarians germ layers

Outer layers are epithelium with jelly like middle called mesoglea

Epithelium contains...

nerve cells and contractile cells

Nerve cells

able to sense outside stimulus and coordinate the animals response

Contractile cells

bend the organisms body allowing it to move through the water

Polyp

Cup shaped tubular body form with a mouth and tentacles at one end and a base that attaches to a hard surface on the other end, sessile

Medusa

Umbrella shaped body with its mouth facing downward and tentacles extending around it, motile (free swimming)

Cnidocytes

stinging cells on tentacles

Nematocytes

coiled tubes containing an attached barb that discharges a toxin when launched

Central digestive system (Cnidaria)

One opening, Enzymes in gut break down food, epithelial cells absorb nutrients, expel waste back out the mouth

Class Scyphozoa

Jellyfish (typically small, motile)

Reproduction (Jellyfish)

reproduce sexually and asexually

Life cycle of Jellyfish

Start as polyp and become more prominent medusa

Class Anthozoa

Sea Anemone and Coral (Only exist in polyp form)

Sea Anemone use...

chemical recognition system to release nematocysts and to form a symbiotic relationship

Coral are...

colonial creatures that produce a limestone cup that the coral polyp can retract into, create coral reefs

Class Hydrozoa

Hydra, Hydroid colonies, and Portuguese Man of War (mostly marine animals, very small, colonial species)

Stem cells

Can differentiate into other cells

Phylum Echinoderm

Sea stars, Sea urchins, and Sea cucumbers

Characteristics of echinoderms

marine animals, spiny skinned animals

Pentaradial symmetry

split 5 ways

Water vascular system

system of tubes filled with water extending through the entire body used for feeding, respiration, movement, and sensation

Sieve plate

filters sea water before entering the system

Ring Canal

where water enters, surrounding the mouth

Radial Canals

extend from the central part of echinoderms body down each ray

Lateral Canals

branch perpendicularly off the radial canals and terminate at tube feel

Tube feet

hollow feet-like knobs used for breathing and movement

Ampulla

muscle structures on the internal side of tube feet

Endoskeleton

an internal skeleton made up of plates called ossicles

Mouth is on the...

bottom side

Anus is on the...

upper side

Open circulatory system

blood flows freely through body cavity

Regeneration

ability to replace damaged areas

Class Asteroidea

Sea Star (have 2 stomachs)

Class Ophiuroidea

Brittle stars

Class Echinoidea

Sea urchins and sand dollars

Class Holothuroidea

Sea cucumbers