CLASS GASTROPODA Flashcards Preview

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Flashcards in CLASS GASTROPODA Deck (37):
1

What are the characteristics of class Gastropoda?

Uni-valved, a-symmetrical, cephalisation

2

Describe the a-symmetrical shell

Coiled and torted

3

What are the tentacles?

They are chemoreceptive

4

What are statocysts?

A small organ for balance and orientation

5

What is an osphradium?

An organ that tests the incoming water

6

What is the planispiral?

An unstable, asymmetrical shell

7

Describe the consequences and solutions of an asymmetric shell

The lengthened shell and cone shape resulted in a stability problem, coiling and torsion solved this

8

What is torsion?

The visceral mass turning 180 degrees

9

Describe the gut shape

'U' shape

10

What is the problem with the gonoduct openings, kidney and anus being above the head?

A sanitary problem

11

What is the solution to the gonoduct openings, kidney and anus being above the head and restricted waterflow?

Tthere's an opening for an exhalent current. Water goes into the mantle cavity & out the opening. e.g. keyhole limpets

12

Describe the shell

Whorls wrapped around central columella, oldest are smallest

13

What secretes the new shell?

The mantle margin around aperture

14

What is the function of the operculum?

Closes the aperture

15

What is the orientation of some shells?

Most are dextral (right coiled), few are sinistral (left coiled)

16

What organism is the excretion, respiration and circulation like?

The generalised mollusc

17

What are the exceptions to the similarities between the generalized mollusk and gastropoda?

The right metanephridium, gill and atrium are lost

18

Explain the changes of the pulmonates as a result of moving onto land

Both gills are lost, the mantle cavity is heavily vascularized and there's a lung

19

Name the structure in a grazer

Radula

20

Name the structure in a hunting carnivore

Proboscis and a simplified gut

21

Name the structure in deposit, filter and suspension feeders

Modified gills, mucus nets and parasites

22

What is the flexible structure or water intake and how is it made?

The siphon, made by the anterior left mantle margin being rolled

23

In what kind of gastropods is the siphon well developed?

Predatory or scavenger snails

24

What other organism is the nervous system in gastropoda like and exceptions?

The generalized mollusk. Exceptions are torsion and cephalisation.

25

Explain the process of torsion

The visceral mass is twisted which brings the mantle cavity and anus to an anterior position above the head

26

Describe the reproduction process in early gastropods

Dioecious and external fertilization

27

What are some other reproduction traits of gastropoda?

Hermaphrodites, internal fertilization and behavior patterns are more complicated

28

What is simultaneous hermaphroditism?

Male and female at the same time

29

What is protandric hermaphroditism?

The individual changes sex at some point in its life, male to female

30

Name the groups of organisms that are simultaneous hermaphrodites

Pulmonata and Opisthobranchia

31

Name the groups of organisms that are protandric hermaphrodites

Prosobranchia (slipper snails

32

Name the groups of organisms that are protandric hermaphrodites

Prosobranchia (slipper snails

33

What kind of larva does archaeogastropoda have?

Planktonic trocophore larva

34

What kind of larva do most other gastropods have?

Derived veliger larva

35

How do veliger larva swim?

Using a ciliated velum

36

What does the veliger larva have before it settles?

A shell and torsion

37

What kind of development does the class Pulmonata have?

Direct