Phylum: Cnidaria Classes: Hydrozoa, Scyphozoa, Anthozoa

Anthozoa Corals

-are colonial polyps -secrete a calcium carbonate "skeleton" -hard coral polyps are hexamerous -soft coral polyps are octamerous -no siphonoglyph

Epidermis

-bases of epitheliomuscular cells contain contractile longitudinal muscle fibers -interstitial cells that give rise to nerve cells

Importance of cnidarians

-corals provide habitat for marine species -turtles and crabs eat jellyfish

Hydrozoa Specimen: Gonionemus

-gastrovascular cavity leads to 4 radial canals that connect to a single ring canal -one gonad hangs from each radial canal -bell margin has many sensory cells containing two types of sense organs: •statocysts=orientation •ocelli=light-sensing

Class Scyphozoa characteristics

-true jellyfish -medusa form is dominant -cnidocytes present in epidermis and gastrodermas -no velum -mesoglea has amoeboid cells

Gastrodermas

Bases of nutritive-muscle cells contain contractile circular muscle fibers

Class Hydrozoa Specimen Obelia

-is colonial -alternates between polyp and medusa(equal forms) -2 types of polyps: •feeding=hydranth •reproductive=gonangium -forming medusa are called medusa buds -reproduction can be sexual or asexual

Hydrozoa Specimen: Gonionemus

-medusa form is dominant -they have a velum(shelf) -have no gastric pouches -no oral arms -mouth is at a single tube called a menubrium -they are dioecious

Cnida

Coiled filament inside an inverted tube

Nematocysts

Venomous harpoon

Class Scyphozoa Specimen Aurelia

-4 oral arms -gastrovascular cavity is folded into 4 pouches -complete network of radial canals and ring canals -bell margin is scalloped with numerous pairs of lap pets, each of which contains a sensory structure called a rhopalium

Tissue Level of Organization

-Digestive tissue -Nervous tissue -Muscular tissue

Phylum Characteristics

-Diploblastic (endoderm and ectoderm) -Most have cnidocytes -Nearly all have planula larvae

Digestion in Hydra and all other Hydrozoans

-Gland cells in the Gastrodermas secrete hydrolytic enzymes -nutritive-muscle cells phagocytize food particles -nutrients are released and diffuse throughout mesoglea -nutrients are absorbed by all other cells

Characteristics of class Hydrozoa

-dominant polyp form -cnidocytes present in epidermis only -very small -medusa, if present have velum, no gastric pouches, no oral arms

Class Anthozoa characteristics

-flowers of the oceans -polyp form only -gastrodermas divided by septa or mesenteries that bear nematocysts -tentacles are solid -may be hexamerous or octamerous

Hydrozoa

-polyp form only -feeding tentacles surround the hypostome, at the center of which is the mouth -the mouth opens into a single, tubelike gastrovascular cavity -body ends in a basal disc

Scyphozoa reproduction

1.medusa 2.zygote 3.planula larva 4.scyphistoma 5.strobila (rattle) 6.ephyla(when it breaks off) 7.medusa

Cnidocyte

Are or can be the stinging cells

Mesoglea

Between endoderm and ectoderm and is a water and collagen based gel

Reproduction for Hydra

Either sexual or asexual through budding: -sexual: eggs are produced in the ovaries, and sperm is produced in the spermaries -embryos encyst, attach to substrate, and young hydra hatch when weather is favorable -most hydras are dioecious(separate sexes)

Hydrozoa Specimen Physalis

Is the Portuguese man o war -not one individual actually hundreds of polyps living together -pneumatophore=float -gastrozooids=feeding polyps each with one single long feeding tentacle -dactylozooids: fishing tentacles fragmented from gastrozooids, filled with nomadic tats -gonophores: reproduction