Lab 3: Cnidaria/Platyhelminthes

Question 1

Cnidarian Germ Cell Layers

Answer 1

contain both an ectoderm and endoderm germ cell layer

Question 2

Cnidarians; diploblastic, or triploblastic?

Answer 2

diploblastic (2 germ cell layers)

Question 3

2 Cnidarian body forms:

Answer 3

polyp & medusa

Question 4

Polyp:

Answer 4

cylinder like body with mouth pointing up, and tentacles waving above; sessile (stationary)

Question 5

Medusa:

Answer 5

Jellyfish bowl shape with mouth pointing down, and tentacles hanging

Question 6

Gastrodermis:

Answer 6

internal tissue layer formed by endoderm

Question 7

Epidermis:

Answer 7

External tissue layer formed by the ectoderm

Question 8

Mesoglea:

Answer 8

Non living gelatinous portion between epidermis and gastrodermis

Question 9

Difference between sponge and cnidarian layers

Answer 9

Sponges have cell layers, Cnidarians have tissue layers

Question 10

Gastrovascular Cavity

Answer 10

inner cavity forms mouth and anus

Question 11

Cnidarian Symmetry

Answer 11

Radial

Question 12

Ends of a Cnidarian

Answer 12

Oral and aboral

Question 13

Support: Sponge vs. Cnidarian

Answer 13

Spicules provide rigid mineral support; hydrostatic skeleton

Question 14

Hydrostatic Skeleton

Answer 14

An enclosed cavity with an incompressible volume of water is surrounded by muscles. Compression of muscles change shape of cavity.

Question 15

Abilities of muscles: 2 abilities, 1 non-ability

Answer 15

Can contract and relax; cannot lengthen

Question 16

Antagonistic Muscles Systems

Answer 16

Two opposing muscles systems; e.g: circular muscles and longitudinal muscles

Question 17

Cnidarians: Obtaining food

Answer 17

Nematocysts: sting prey and lure into gastrovascular cavity

Question 18

Cnidarians: Feeding strategy

Answer 18

Batch feeding

Question 19

Batch Feeding

Answer 19

because there is only one cavity which serves as a mouth and anus, Cnidarians eat a lot at once, digest it, then expel waste through the same hole. These kind of animals CANNOT continuously feed.

Question 20

Cnidarians: Gas Exchange

Answer 20

Diffusion across 1 cell thick external and internal layer. Direct respiration with environment via gastrovascular cavity and external water. No special organs.

Question 21

Cnidarians: Circulation

Answer 21

Cells in direct contact with environment. Cilia will create water currents in gastrovascular cavity.

Question 22

Cnidarians: Sensory Nervous System

Answer 22

No central system; diffuse net allows partial sensing, and balance, partial light sensors

Question 23

Cnidarians: Excretion of Waste

Answer 23

Cells can directly expel waste to environment

Question 24

Zooxanthellae

Answer 24

Single celled marine algae ingested by Cnidarians. Zooxanthellae provide photosynthetic energy, and receive nutrients like nitrogen and phosphorous.

Question 25

Platyhelminthes: Classes

Answer 25

Flatworms, tapeworms, flukes

Question 26

Platyhelminthes: Tissues

Answer 26

Ectoderm, endoderm, and MESODERM layer

Question 27

Mesoderm Layer:

Answer 27

Contains well developed muscle and organ tissue. Living tissue, unlike the Cnidarian mesoglea.

Question 28

Platyhelminthes: Support and Movement

Answer 28

contains a living hydrostatic tissue called “mesenchyme tissue”.

Question 29

Platyhelminthes: Nervous system

Answer 29

Ganglia centered anterior, 2 longitudinal nerve cords in a “ladder” shape. Also eyespots.

Question 30

Platyhelminthes: Waste Management & Concentration control

Answer 30

Nitrogen diffused out of cells as ammonia, fluid enters through “protonephridia” structures that alter concentrations necessary for the body.

Question 31

Platyhelminthes: Digestion and circulation

Answer 31

Multiple ways, e.g: pharynx tube, one entrance. Gastrovascular cavity highly branched, allowing direct diffusion into cells from water.

Question 32

Platyhelminthes: Reproduction

Answer 32

Asexually by splitting into 2 parts and regenerating. Hermaphroditic: can produce egg and sperm, but do not fertilize themselves.