Lesson 22b

Question 1

What is class Gastropoda?

Answer 1

Gastropods (meaning stomach foot)

slugs, conchs, abalones, nudibranchs, whelks, dowries, murexes, and snails

Question 2

Gastropods are usually referred to as…

Why?

Answer 2

Univalves, because most have a single shell

Question 3

Explain the structure of Gastropods…

Answer 3

1. Most have a single shell (univalve)
2. Muscular foot used for movement by creating muscular contractions over a bed of mucous
3. Head
   a) Two pairs of tentacles: one pair used for feeling, and the other pair may end in eyes
   b) Radula: rough, tongue-like organ used to scrape food into their mouth and carry it to the digestive tract

Question 4

What is class Cephalopoda?

Answer 4

The Cephalopods! (meaning head foot)

Nautilus, cuttlefish, squid, and octopus

Question 5

Explain the structure of Cephalopods…

Answer 5

1. Well developed head with many tentacles or feet
2. Beak-like jaw
   a) Allows them to tear prey into pieces
   b) Radula moves the food to their esophagus
3. Mantle is an outer body wall covering the visceral hump
4. Elongated visceral hump above their head

Question 6

How do Cephalopods move?

Answer 6

1. Water is sucked into the mantle cavity covering the gills.
2. Mantle constricts, trapping the water inside their body.
3. Water can exit quickly through a funnel below their head allowing them to move via jet propulsion

Question 7

Explain a Cephalopod’s nervous system…

Answer 7

Their system is well developed

a) Large brain
b) Complex eyes, resulting in excellent vision

Question 8

Explain a Cephalopod’s circulatory system, if they have one…

Answer 8

They have a closed circulatory system

a) Blood vessels that move blood through their body
b) Two branchial hearts which move the deoxygenated blood to the gills
c) One systemic heart which pumps the oxygenated blood throughout the body

Question 9

How do Cephalopods reproduce?

Answer 9

They reproduce sexually

a) Most only reproduce once because both male and female typically die shortly after mating.
b) Female cephalopods do not eat while caring for their eggs, dying shortly after the eggs hatch

Question 10

Explain Cephalopods inking…

Answer 10

They use Inking as a defense mechanism

1. They produce dark ink stored in an ink sac they can blow at their predators, acting as a diversion
2. Ink acts as an irritant that can cause blindness in some organisms.

Question 11

Lesson 22b summary…

Answer 11

file:///C:/Users/trgan/Sync/LisA%20school/Lesson%2022b%20Phylum%20Mullusca%20summary.mp4

Question 12

What is the largest known invertebrate?

Answer 12

Colossal Squid

Question 13

What is the only cephalopod with an external shell?

Answer 13

Nautilus