Bio 1413 Final * Phylum Cnidaria

Front 1

Skin layers

Back 1

Epidermis [outer covering]
Mesoglea [middle layer]
Gastrodermis [inner lining of gv cavity]

Front 2

Basic Body Structures

Back 2

Polyps -- tubelike forms that are attached to substrate
Medusa -- umbrella-shaped forms that are free-swimming; mouth and tentacles project downward

Front 3

Integument

Back 3

Simple epidermis w/ several distinct cell types
Epitheliomuscular cells
--> basic cell type in the epidermis
Interstitial cells
--> newly developing cells

Front 4

Cnidocytes?

Back 4

Specialized defensive cells found only in Cnidaria **
Contain nematocysts which are expelled when the lid [operculum] opens due to a stimulus

Front 5

Neurosensory Cells

Back 5

A network of cells that transmit impulses, is termed a nerve net
Also found in gastrodermis

Front 6

Skeletal System

Back 6

Chitinous -- hydroids
Aragonite -- stone like CaCO3/ stony corals
Combinations of protein [gorgonin] and crusty CaCO3--soft corals

Front 7

Muscular System

Back 7

Two types of cells:
Epitheliomuscular cells -- contractions of the longtiudinal myofibrils cause the body to shorten
Nutritive muscular cells -- gastrodermis layer; dual function;

Front 8

Feeding and Digestion

Back 8

Are predatory.
Nematocysts are discharged to paralyze the prey during capture

Front 9

Digestion

Back 9

Begin digesting once inside GV cavity; gastrodermis responsible for digestion
1st stage) Extracellular Digestion
--> Gland cells in the gastrodermis release enzymes to GV cavity which start break down of food
--> Absorbed by nutritive muscular cells
2nd stage) Intracellular Digestion
--> Within the nutritive muscular cells, formation of food vacuole then fusion with a lysosome

Front 10

Statocysts

Back 10

Each a small invaginated pocket lined by "hair cells; also contains tiny calcaerous granules which roll around as the animal swims and stimulates the hair cells; when hair cells are stimulated, nerve impulses are generated

Front 11

Sensory Structures cont

Back 11

Ocelli -- clusters of photoreceptor cells, these measure light intensity, but do not form any images
Rhopalia -- found in jellyfish, a rudimentary sense organ consisting of both statocysts and photoreceptor cells

Front 12

Class Hydrozoa

Back 12

Hydras, hydroids, fire corals
Simple GV cavity
No pharynx
Buds develop laterally

Medusa Characters
--> Four radial canals, simple oral lobes, posses a velum, gonads epidermal

Front 13

Class Cubozoa

Back 13

Polyp:
--> Simple GV cavity, no pharynx, polyp transforms into medusa
Medusa:
--> cube-shaped, four tentacles arising from corners, have a structure similar to velum

Front 14

Class Scyphoza

Back 14

Polyp:
--> Simple GV cavity, no pharynx, buds develop terminally
Medusa:
-->No velum

True Jellyfish

Front 15

Class Anthozoa

Back 15

Ex: soft corals, stony corals
Polyp:
--> partitioned GV cavity [chamber is divided by membranes called mesenteries or septa]
--> tube-like pharynx
--> gonads present on polyp, gastrodermal
--> ** absent medusa stage

Two Subclasses:
Subclass Alcyonaria
--> polyp has 8 pinnate [feathery] tentacles; skelton of gorgonin + CaCO3
Subclass Zoantheria
--> tentacles in multiples of 6; skeletons calcaerous