Cnidarians

Question 1

Classes of Cnidarians

Answer 1

C. Hydrozoa, C. Cubazoa, C. Scyphozoa, C. Anthozoa

Question 2

Types of symmetry

Answer 2

Radial and Biradial

Question 3

Tissues

Answer 3

Epidermis and Gastrodermis, and so they are diploblastic

Question 4

They have polymorphisms.

Answer 4

Medusa(sexual) and Polyp (Asexual)

Question 5

Between the epidermis and gastrodermis is?

Answer 5

Mesoglea

Question 6

We have extracellular digestion.

Answer 6

There is a gastrovascular cavity that continues through the tentacle

Question 7

Hydrostatic Skeleton

Answer 7

The skeleton is supported by water

Question 8

There are nerves

Answer 8

There is a nerve net and nerves that make the myofibrils contract.

Question 9

In the epidermis, what is the most common cell?

Answer 9

The epitheliomuscular cell. They have myofibrils that allow them to contract

Question 10

What are interstitial cells and where are they found?

Answer 10

In the epidermis, and they give rise to other cells

Question 11

Cnitocytes

Answer 11

The warrior of cells. If the cnidocil is triggered then the nematocyst is discharged. This occurs by a change in the cell’s permeability in water

Question 12

What cells are found in the gastrodermis?

Answer 12

We have nutritive muscular cells. They are involved in digestion, enzyme secretion, and may take up nutrients.

We also have gland cells which produce mucus

Question 13

Types of nematocysts

Answer 13

defendant, penetrant, adherant

Question 14

Class Hydrozoa

Answer 14

Polyp is dominant. They may be solitary or live in groups (obelia). Medusa has a form of the velum that allows for better thrust

Question 15

Genus Obelia

Answer 15

Obelia is colonial, Has a gastrozoid for eating and tentacles
Inside the polyp is the coenosarc
Gonozoid for asexual reproduction
For sexual, male and female have their own organs. They fertilize, the thing develops into a planula—> develops into new polyp. Alt of gen. Has polyphase perisarc, non living outer layer that is used for protection.

Question 16

Physalia - Portuguese man of war

Answer 16

Has specialized polyp called pneumatophore which aids in floatation, Still has gastro/gonozoid, but now has specialized tentacles called dactylozooids used for fishing. Colony made up of many polyps

Question 17

Gonionemus (Hydroid Medusa)

Answer 17

The medusa is the dominant form.
They have a statocyst that has a little grain of sand that aids in balance.
Food gets in through the mouth and into the manubrum –> gastrovascular cavity–> radial canals –> Ring Canal –> then tentacle.

Question 18

Class Cubozoa

Answer 18

They have a reduced polyp. They are square shaped. They have a pedalium, fleshy part that supports the tentacle. Can herd their prey. The box jelly fish (Chironex fleckeri) can cause Irakandji syndrome

Question 19

Class Scyphozoa

Answer 19

Medusa is the dominant form. these are our classic jelly fish. The life cycle can be seen through Aurelia.
Learn that
It has a rhopalium- that includes a statocyst, ocelli (eyes) and chemosensory pits. These are seen around the base of the jelly.

Question 20

C. Anthozoa

Answer 20

These are just anemones and corals. They are polyp only and all marine. They give rise to coral reefs.

Specific Ex. is Metridium

Question 21

Metridium

Answer 21

From class anthozoa, they have an oral disc and pharynx that is supported by primary septa. Secondary septa aid in absorbing nutrients
They have hydrostatic skeleton, redused mesoglea.
Around the oral groove is the siphonoglyph, used for bringing in water
Inside the gastrovascular cavity is the acontia which will shoot out in self defense
They have a symbiotic and mutualistic relationships
They have symbiotic algae called Zooxanthellae

Question 22

Corals

Answer 22

Part of the anthozoa.

Stony Corals= zoantherian
Produce a lot of calcium carbonate with the aid of algae
With these, they have six septae,
they are hexacoralian

We also have octocorals which are out soft ones. They have 8 septa and they don’t have the hard calcium carbonate components. The polyps communicate through channel pathways called solenias.

Question 23

Types of Reefs

Answer 23

Lagoon (No islands)
Barrier (runs parallel to the shore)
Fringing (No gap)