Mollusca: Gastropoda

Question 1

Synapomorphies (4)

Answer 1

asymmetrical body due to torsion- 180 degree twist of
the body during development;

mantle and anus is above the head,

single
spiral shell,

well developed head with tentacles, eyes, and radula, muscular
foot

Question 2

body wall (2) and support

Answer 2

Body wall: covered by a mantle with shell in some species;

those without
a shell have a mucus layer

Support: shell or hydrostatic skeleton

Question 3

locomotion (2) and body cavity

Answer 3

Locomotion: muscular foot or jet propulsion;

others swim using wing-like
parapodia

Body cavity: reduced coelom and a hemocoel

Question 4

feeding/ digestion (2) and circulation (2)

Answer 4

Feeding: food depends on species; uses radula to feed

Digestion: well-developed digestive system with a coiled intestine;

some
use symbiotic bacteria to digest

Circulation: open circulatory system in most, while cephalopod-like
gastropods have a closed system;

hemolymph

Question 5

excretion and gas exchange

Answer 5

Excretion: Nephridia filters wast

Gas exchange: uses either ctenidia or vascularized mantle cavity

Question 6

nervous system (2)

Answer 6

well developed with a ganglia;

eyes and statocysts for
balance

Question 7

reproduction (2) and development (2)

Answer 7

Reproduction: some are dioecious, others are hermaphroditic;

internal and
external fertilization

Development: most have a trochophore larvae,

while some bypass the
larval stage

Question 8

habitat (4)

Answer 8

Marine- snails, limpets

Freshwater- pond snails

Terrestrial- land snails and slugs

Requires a moist environment

Question 9

fun fact

Answer 9

Few groups successful in ocean, freshwater, and land