Invertebrates 3

Question 1

What is the coelom? What happens there?

Answer 1

Main body cavity in animals that is filled with fluid and lined with the mesoderm. Place where nutrient and oxygen exchange can occur and where internal organs can move independently.

Question 2

Cnidarians?(symmetry, diploblastic or triploblastic)

Answer 2

-Radially symmetrical
-Diploblastic(2 germ layers)
-Stop embryonic development after the gastrulation stage
-Simple nervous and muscles tissues
-Sensory information can come in from any direction

Question 3

Body plan of the cnidarian(two orientations)

Answer 3

Polyp:
- mouth is upwards
- sessile form
- Trunk covered by an oral disc and has tentacles around its mouth
-Radially symmetrical
Medusa:
- mouth is downwards
-Motile form
-Radially symmetrical

Question 4

Life cycle of Cnidarians

Answer 4

-Life cycle includes both medusa and polyp body plans.
-Polyp(asexual stage)
-Medusa(sexual stage)

Question 5

How do cnidarians obtain energy?

Answer 5

• Cnidocytes located near the mouth or on the tentacles of cnidarians can detect prey, when they do they will inject a spear like nematocyst which contains toxins and barbs into the prey.
  -The barbs of the cnidocyte hold the prey in position and the toxins subdue the prey until it is fully digested

Question 6

What are the four major groups of cnidarians?

Answer 6

1. Hydrozoa
2. Scyphozoa
3. Cubozoa
4. Anthozoa

Question 7

Hydrozoa

Answer 7

• No medusa stage(polyp stage must be motile)
  -Net like nervous system that can receive and send signals in any direction
  Ex. Portuguese man of war

Question 8

Scyphozoa

Answer 8

-Large mesoglea(layer between the epidermis and gastrodermis)
-Arms around the mouth are equipped with nematocys
-True jellyfish

Question 9

Cubozoa

Answer 9

-Box jelly fish
-Deadly sting

Question 10

Anthozoa

Answer 10

-No medusa phase
Ex. anemones
- Mutulastic relationship with clown fish(provides shelter keep predators away)
-Tentacles have cnidocytes
Ex. corals
- mutualistic with dinoflagellates

Question 11

What is a protostome?

Answer 11

Organism who’s mouth develops from the blastopore and who’s coelom forms from the splitting of the mesoderm.

Question 12

What is a deuterostome?

Answer 12

Organism who’s anus develops from the blastopore, coloem and mesoderm form from outgrows of the primitive gut

Question 13

Why is coral bleaching occurring?

Answer 13

-Increase in water temperatures
-Disease
-Increase in UV radiation
-Pollution

Question 14

What is a coelomate?

Answer 14

Organisms with an enclosed body cavity completly lined with mesoderm (outside and inside of the cavity its lined)
Example: annelids, mollusks

Question 15

What are the three different types of body cavity formations?

Answer 15

1. Coelomate
2. Acoelomate
3. Pseudocoelomate

Question 16

What is an acoelomate?

Answer 16

An organism with no body cavity in the mesoderm. Lost their coelom
Example: flatworms

Question 17

What is a pseudoecoelomate?

Answer 17

An organism with a fake coelom, the mesoderm only lines the outside of the cavity and not the inside.
Ex. Nematodes and Rotifers

Question 18

Can diploblastic animals have a coelom?

Answer 18

NO!! Diploblastic animals don’t have a mesoderm therefore they can’t have a coelom only triploblastic animals can.

Question 19

How do protostomes form the coelom?

Answer 19

The coelom is formed through a process called schizocoely, where the mesoderm splits.

Question 20

How do deuterostomes form the coelom?

Answer 20

The coelom is formed through a process called enterocoely, where the mesoderm forms pocket from the gut.

Question 21

Protostomes vs Deuterostomes

Answer 21

Protostomes:
- Blastopore - mouth
- Coelom form by schizocoely
-Spiral cleavage
Deuterostomes:
-Blastopore - anus
- Coelom formed by entercoely
- radial cleavage

Question 22

Where does gas exchange occur if there is no coelom?

Answer 22

The gas exchange must occur through the body surface

Question 23

If the mouth developped first what type of organism is it?

Answer 23

Protostome

Question 24

Cephalization

Answer 24

Concentration of sense organs and ganglia near the front end of the organisms(sense structures: taste, smell, etc.)

Question 25

Blind Gut?

Answer 25

One opening for both digestion and food

Question 26

Ectoparasitic

Answer 26

Parasite that lives on the external surface of a host