Cnidarians

This set is on the cnidarian lab

what type of symmetry can you find in this phylum?

Radial symmetry

what are some examples of Cnidarians

Jelly fish, sea anemones, and corals

Where does the phylum get its name from?

Cnidocytes, which are stinging cells

What make the cnidarians special?

Diploblastic ( two germ tissues

tissue level of organization

have a digestive cavity

radial symmetry

They are the first to have?

a digestive cavity, with a mouth and extracellular digestion

What type of apomorphy do they have?

cnidocytes

How do cnidocytes work?

it is a nematocyst with a stored thread and barb. When the hairlike projection gets touched it shoots out and stuns the prey.

What does it mean to have an incomplete gut?

to only have one opening serving as both mouth and anus

What is the gastrovascular cavity?

the gut for cnidarians

What are the two main body types?

Polyp or medusa

What is the difference between a polyp and medusa?

A polyp is sessile and the Medusa is mobile

What are the six classes?

Hydrozoa, Scyphozoa, Anthozoa, Myxozoa, staurozoa, and cubozoa

Hydrozoa

Water animals, that go through both polyp and medusa stage.

What is a defining characteristic of the Hydrozoa class?

The presence of a velum at the bottom of the exumbrella. ( makes it hole the umbrella shape)

Scyphozoa

True Jelly fish that alternate between polyp and medusa stage

What is the defining characteristic of the Scyphozoa class?

Lack Velum, so they can completely flatten.

Anthozoa

Flower animals, and only have the polyp stage which sets them apart of the other classes. They can detach themselves and float to a different location and reattach themselves

True or false: anthozoa are both colonial or solitary.

True.

Myxozoa

smallest animal to live, sometimes single celled. DNA evidence and presence of nematocyst like capsule is white they are a part of this phylum

Staurozoa

Stalked jellyfish who only have a medusa stage but are attached to a stalk which makes them look like a polyp

Cubozoa

Cubed shaped jellyfish

What type of animals are in the Hydrozoa class?

Obelia, Portuguese man o’ war

What type of animals are in the scyphozoa class?

The moon Jelly

Which cnidarians are a colony of polyps?

Portugues man o’war and the sea pansy

Describe the reproduction cycle of the moon jelly

The egg and sperm unite to form a planula larva that attaches to a substrate and grows into a scyphistoma. Then it undergoes strobilation and eventually release an ephyrae.

What is the planula larva?

the union of the sperm and egg in the Scyphozoa class.

Scyphistoma

when the planula larva attaches itself to the substrate in a reduced polyp form

How does the scyphistoma reproduce?

Asexually via strobiliation

Strobila

the multiple stacked medusa, like plates

Ephyrae

immature medusa releseaed after strobilation

Rhopalia

sense organs, found in the notches of the lappets in the ephyrae

ocellus

light sensation in the rhopalia

statocysts

gravity sensation in the rhopalia

Label the fine tentacles, 4 long oral arms, GVC, gonads,

refer to image

Label the coenosarcs, hydrants, and the gonangium on the obelia

refer to image

coenosarcs

where obelia polyps grow on

Hydranth

the feeding polyp of obelia

gonangium

the reproductive polyp with tiny immature medusae inside

Label the GVC and the gonads on the obelia

refer to image

On an adult hydrozoan label the mouth, gonads, tentacles and velum and 4 radial canals

Refer to image

anthozoa animals

these are corals

What is a polyp on a coral

it is the space where a coral had a symbiotic relationship with a zooxanthellae

how do you know how many zooxanthellae once lived on a coral?

You can estimate by the amount of holes on a coral.