Animal Organization

Question 1

Radial body symmetry

Answer 1

cut through the centre and can make 360 degree mirror images. These animals can sense the env. 360 and typically don’t move

Question 2

Bilateral body symmetry

Answer 2

has symmetrical sides on a unique plane

Ex. A human is bilateral longitudinally

Question 3

3 different types of embryonic germ layers

Answer 3

None: no true tissue

Diploblastic: “diplo” = 2 germ layers (tissue); “blastic” = early in development. Consists of ectoderm and endoderm

Triploblastic: the animal has all 3 germ layers (ex. humans). Consists of ectoderm, mesoderm, and endoderm

Question 4

True tissues

Answer 4

Basement layer is present. Basement layer is formed when tissues are forming new tissues, thus making a barrier

Question 5

Coelom

Answer 5

A hollow and fluid-filled cavity that runs throughout the invertebrate. It separates the body into an inner and outer tube. It allows internal organs to move and grow independently of the outer layer of the body wall

Question 6

Mesenchyme

Answer 6

Derived from mesoderm. Consists of living cells in a mesh of proteins and fluid

Question 7

Lumen

Answer 7

Inside space of tubular structure that’s continuous with the outside world

Question 8

Endoderm

Answer 8

Innermost layer of the 3 germ layers. Gives rise to the gut

Question 9

Ectoderm

Answer 9

Outermost layer of the 3 germ layers. Gives rise to the “skin”

Question 10

Mesoderm

Answer 10

Germ layer formed during gastrulation. Forms between the ectoderm and endoderm

Question 11

Gastrodermis

Answer 11

Derived from endoderm. The lining membrane of the digestive tract or gut of an invertebrate

Question 12

Epidermis

Answer 12

Derived from ectoderm. A single layer of cells that act as a protective layer of “skin”

Question 13

Mesoglea

Answer 13

Derived from mesoderm. A gelatinous substance between the ectoderm and the endoderm. Contains no living cells

Question 14

Mesentary

Answer 14

Fold of membrane that attaches the intestine to the abdominal wall and holds it in place. Provides structural integrity

Question 15

Acoelomate

Answer 15

Invertebrates lacking a coelom

Question 16

Coelomate

Answer 16

Invertebrates have a coelom

Question 17

Blastocoelomate (or Pseudocoelomate)

Answer 17

Invertebrates that have false body cavities. They have a fluid-filled body cavity that separates the gut from the body wall, but it isn’t line by mesoderm (ie. the peritoneum) like true coelomates

Most animals with this body cavity will be small and may be in a hard, robust shell

Question 18

Peritoneum

Answer 18

Derived from mesoderm. Lining of the coelom