Phylum Cnidaria

Question 1

How many tissue layers have cnidarians?

Answer 1

They Are diploblastic: ectoderm (skin, protection and structure) and endodermis (gastrodermis and gland cells)

Question 2

How the nerve net is on cnidaria?

Answer 2

They have a simple nervous system, no brain or any form of cephalisation.

Question 3

How cnidaria can live?

Answer 3

They can be in individual pollos or colonial polyps.

Question 4

Characteristics of polyp form

Answer 4

Sessile(attached to substrate), cylindrical body, tentacles surrounding the mouth, sexual and asexual (budding) reproduction.

Question 5

Characteristics of medusa form

Answer 5

Free-swimming, bell-shaped body,mouth directed downward, tentacles on periphery of bell and sexual reproduction

Question 6

What Are nematocysts?

Answer 6

Tentacles in some cnidarians have stinging cells. It is a structure containing a spirally folded, venom-filled thread with a sensor

Question 7

What Are zooxanthellae?

Answer 7

Are single-celled algae that live in the tissues of animals (mutualistic relationship)

Question 8

Characteristics of Hydrozoa

Answer 8

They Are predators, mostly marine but some Are freshwater (hydra), solitary or colonial.

Question 9

Characteristics of Hydra sp.

Answer 9

Solitary polyp, freshwater, cylindrical tube with tentacles with a basal or pedal disc, able to move.

Question 10

Characteristics of physalia physalis

Answer 10

Colony of polyp individuals with particular tasks: dactylozooid (capturing tentacles), gastrozooid(feeding polyp), gonozooid (reproductive polyp) and one polyp filled with gas to float.

Question 11

Characteristics of class Scyphozoa

Answer 11

All marine, “true jellyfish”, life cycle with polyp and medusae form, four gastric pouches, rhopalium(sense containing statocysts and sometimes ocelli).

Question 12

Aurelia lifecycle

Answer 12

Medusae release eggs and sperm- fertilized eggs develop into planula larva-larva settles on substrate and develops into polyp- scyphistoma produces a series of polyps by budding, polyps develop and released from strobila as free swimming ephyra -ephyra matures into a jellyfish

Question 13

Characteristics of class cubozoa

Answer 13

All marine, cube-shaped medusa with tentacles arising from each corner, medusae stage dominate, bell margin with a velarium, rhophalia with ocelli and statocysts, predators (stings can be fatal).

Question 14

Characteristics of class Anthozoa

Answer 14

All marine, solitary or colony, polyp form only, predators and have a symbiotic relationship with zooxanthellae

Question 15

What composes order Hexacorallia?

Answer 15

Anemones and hard corals

Question 16

What composes Octocorallia?

Answer 16

Includes soft corals

Question 17

Characteristics of anemone

Answer 17

All marine, solitary polyp, attach to substrate by pedal disc, cylindrical body, hydrostatic skeleton, Are predators and have a symbiotic relationship with zooxanthellae , sexual and asexual ( budding, pedal laceration and transverse fission)

Question 18

General features of hard corals

Answer 18

Tentacles 6 or multiples of 6, all marine, solitary or colonial, rigid skeleton of calcium carbonate, cylindrical body, hydrostatic skeleton, carnivores

Question 19

General features of soft corals

Answer 19

8 feathery tentacles, all marine, colonial only and attached to substrate, cylindrical body, fleshy internal skeleton, hydrostatic skeleton, carnivores

Question 20

Characteristics of class Staurozoa

Answer 20

All marine, only medusa stage, medusa is trumpet shaped with thin disc, in sexual reproduction releases gametes in water column, planula larvae is not free swimming

Question 21

Characteristics of cnidaria

Answer 21

Eumatozoa (have true tissues), acoelomate, hydrostatic skeleton, mostly marine, radially symmetrical, polymorphism (polyp& medusae), planula larvae, single body cavity (gastrovascular), no organ systems, sensitive to touch, carnivores and cnidocytes(stinging cells)