Types of Cnidarians
Polyp

Medusas

(Ex. Platyhelminthes)

Pseudocoelomate: A fluid-filled body cavity separates the digestive tract and outer body wall.

(Ex. Round worms, Rotifers)

Coelomate: Fluid-filled body cavity completely lined with mesoderm.

(Ex. Everything else.)
Blastopore: first opening of the archenteron
A. Protostome:  (mouth first)

nSpiral cleavage: planes of cell division are diagonal to the vertical axis.

nDeterminate cleavage: The development fate of each cell is established early.

(Ex. Mollusca, Annelida)

nRadial Cleavage: cell division that is parallel or perpendicular to the axis.

nIndeterminate cleavage: The tendency of a cell to be able to form an embryo if broken off.

(Ex. Echinodermata, Chordata)

2.Animal  cells lack cell walls that give support to plant and fungi cells.

3.Animals have both nervous and muscular tissue.

4.Animal reproduce sexually with the diploid state dominating the life cycle.

5.Transformation of the zygote is dependent upon controlled expression of the embryo.

·        Have porous bodies (do not have specialized tissues)

·        Characterized by special cells called coanocytes

·        Body Plan

o   Large sac with holes throughout the sides.

o   Water is drawn into large central cavity called the spongocoel and let out through the large hole on the top called the osculum. 

o   Currents are formed and food trapped by flagellated cells called Choanocytes which line the spongocoel.

§  Also called Collar cells.

o   Amebocytes wander throughout the inner cells transporting nutrients and form spicules for support.

·        Reproduction

o   Sponges are hermaphrodites

o   Male and female gametes are formed.

o   Male gametes disperse into the water column and female gametes stay inside the organism.

o   Male gametes will fertilize the female gametes and a larvae is formed.

o   Larvae are pelagic and swim to a new site to start a new organism.

·        Diploblastic 

·        Gastrovascular Cavity:

o   Sac within a sac body plan.

·        Cnidocysts

o   Used to catch food.

·        Body Plan

o   Polyp

§  Sessile in location, these body types will sit and wait for prey to come by

·        Hydras and anemones

o   Medusas 

§  Flattened mouth down versions and passively drift with the current

·        Sea jellies

o   Important Characteristics

§  Cnidarians are carnivorous and use tentacles to push food into their gastrovascular cavity

·        Nematocysts are stinging cells that project needle shaped stingers into prey that inject poison killing or inhibiting them

·        Tripoblastic

o   Flatworms

o   Tape worms

·        Have a sac body plan

o   Flat worms has a single opening

o   Tape worms do not have a digestive tract

·        Planarians

o   Lack organs for gas exchange and circulation

o   Moved by cilia located on their ventral surface

o   More complex nervous system

§  Able to change behavior to stimulus

o   Have two eyespots and lateral slits used for smell

o   Asexual reproduction through regeneration

o   Sexual reproduction but hermaphrodites

·        Flukes (Trematoda)

o   Parasites

o   Life cycle integrates asexual and sexual reproduction

o   More than one host is usually targeted

·        Trinularians

o   Inhabit freshwater streams and marine type environments

o   Scavengers and carnivores

·        Tapeworms

o   Parasitic

o   Live in vertebrates

o   Absorb nutrients directly from the host

·        Lack a circulatory system

·        Tough outer coat

·        Many are parasites to plants and animals

·        Soft bodied animals, some contained within shells

·        Body plan 

o   Mantle

§  Secretes the shell

o   Visceral Mass

§  Most of the internal organs are located except the gills, and anus

o   Muscular Foot

§  Used for locomotion

·        The whole torsion thing

o   Terrestrial snails

o   Torsion is the flipping of the body 180 degrees

uHave a muscular foot that can be extended for movement

uTwo part, hinged shell

uComplete, one-way digestive tract with a mouth & anus

uSeparate sexes
uNo eyes or distinct head

uHave siphons to circulate water through their bodies

uFilter feed on plankton

uMussels are large and have a flat, more oblong shell shape, while freshwater clams are smaller (3/4 inch) and typically more round 
uProtostomes – blastopore becomes the mouth

uHave a fully lined body or mantle cavity

uBody organs called visceral mass protected by mantle which secretes the shell

uOpen circulation

uMost are sessile or sedentary

uIncludes clams, oysters, scallops, & mussels

•        Exoskeleton of Calcium carbonate

•        Water vascular system with tube feet for movement.

•        Echinodermata are all marine, triploblastic unsegmented coelomates

•        Phylum has 3 unique features:

•         pentagonal symmetry (bilateral in larvae)

•        Calcite spicules embedded in the skin, often partly fused

•        Tube feet (podia)

•        Water Vascular system

•        Complex system of watter filled canals

•        Extensions of tubed feet

•        Modification of the coelom

•        Ciliated internally

•        Tube feet

•        Extensions of the canal system

•        Usually emerge through openings in skeletal ossicles

•        Also permit exchange of respiratory gases and nitrogenous waste

•        Sensory functions

•        Nervous System

•        Echinoderms have a diffuse nervous system with no “brain”

•        nerve ring that encircles the mouth

•        radial nerves that extend to each arm

•        coordinate the functions of tube feet

•        nerve net that coordinates the function of the body wall

§  Stiffening

§  Axis for muscle attachment

·        Hollow Dorsal Nerve Chord

·        Pharyngeal Gill Slits or Pouches

·        Post – Anal Tail

What phylum describes protozoans in the evolutionary tree?
rotifera

Describe the spongocoel.
the large, central cavity of sponges. Water enters the spongocoel through hundreds of tiny pores (Ostia) and exits through the larger opening (osculum).

Describe the choanocyte.
a flagellated cell with a collar of protoplasm at the base of the flagellum, numbers of which line the internal chambers of sponges.

Describe the osculum.
a large aperture in a sponge through which water is expelled

What phylum is represented by being diploblastic and have radial symmetry?
cnidarians

Describe the gastrovacular cavity.
The gastrovascular cavity is the primary organ of digestion and circulation in two major animal phyla: the Cnidaria (including jellyfish and corals) and Platyhelminthes (flatworms). The cavity may be extensively branched into a system of canals.

Describe the nematocysts.
A characteristic cnidarians have that are unique stinging structures found within cnidocytes, specialized cells in the tentacles

•But the digestive system, nerve cords and circulatory system run the whole body.

•Have a closed circulatory system.
•Hermaphrodites

•Excrete waste by metanephridia.

•Reproduction is sexual but they are hermaphrodites.

•Some worms can go through asexual reproduction via regeneration.(a type of excretory gland found in many types of invertebrates such as annelids, arthropods and mollusca)

–Jointed appendages, Hard exoskeleton, Body segmentation.
•Defining Characteristics

–Epidermis produces a segmented, jointed and hardened chitinous exoskeleton with musculature between individual joints of appendages
•Phylum includes crustaceans, insects, and chelicerates

•Chelicerates 

–Primarily terrestrial

–Also horseshoe crabs and sea spiders

•Crustaceans 

–Marine and freshwater, absent from land
•Arthropods have segmented bodies with some or all of the segments bearing jointed appendages
•All arthropods have a chitinous jointed exoskeleton
•Simple eyes 

–Light sensitive cells share a common lens

•Compound eyes

–Thousand of closely packed units called ommatidia 

Respiration and circ. system
•Extensive surface areas are needed to supply the large oxygen demands of most arthropods

–Gills can occur both inside and outside of the of the carapace

•Circulatory System

–Open circulatory system as in molluscs, hearts vary in structure but do exist 

–Blood is pumped into empty spaces bathing the tissues in blood