Early Animals

Question 1

Animals

Answer 1

Members of a group of multicellular eukaryotic organisms, characterized by their ability to move from place to place and by how they feed on other organisms

Question 2

Choanoflagellates

Answer 2

Organisms that possess a simple flagellum surrounded by a collar structure composed of microvilli for obtaining food

Question 3

Choanocytes

Answer 3

Cells similar to choanoflagellates that are found within sponges and are used to filter food from the surrounding water

Question 4

Parazoa

Answer 4

The clade (group) of animals that sponges belong to

Question 5

Porifera

Answer 5

The phylum that sponges belong to, named after the numerous pores (ostia) found throughout a sponge’s body

Question 6

Mesohyl

Answer 6

A gelatinous layer that separates the inner and outer layers of a sponge’s body

Question 7

Spongocoel

Answer 7

The inner central cavity of a sponge

Question 8

Amoebocytes

Answer 8

Amoeba-like cells that break down and distribute food to other cells within the sponge

Question 9

Spicules

Answer 9

Spike-like structures released by amoebocytes that aid in supporting the sponge. They are either composed of silica, calcium carbonate, or a flexible protein material called spongin

Question 10

Hermaphroditic

Answer 10

Able to produce both sperm and eggs in the same organism

Question 11

Eumetazoa

Answer 11

Meaning “true later animals”, aside from the sponges, the rest of the animal kingdom is grouped under this clade

Question 12

Diploblastic

Answer 12

Containing two tissue layers

Question 13

Cnidaria

Answer 13

A phylum that contains members known for having specialized cells called cnidocytes

Question 14

Cnidocytes

Answer 14

Specialized cells that contain nematocysts, which are released when stimulated and are used to entangle prey items and inject a stinging or paralyzing toxin into the prey

Question 15

Epidermis

Answer 15

Outer layer in Cnidaria that protects the body

Question 16

Gastrodermis

Answer 16

The layer in Cnidaria that aids in digestion

Question 17

Mesoglea

Answer 17

An acellular, gelatin-like layer that separates the ectoderm and mesoderm tissues of Cnidaria. They possess an opening leading into the gastrovascular cavity

Question 18

Gastrovascular cavity

Answer 18

The cavity where digestion takes place, this is a single opening that acts as both a mouth and anus

Question 19

Hydrostatic skeleton

Answer 19

A cavity such as the gastrovascular cavity that is filled with water and supports the body

Question 20

Planula larva

Answer 20

In Cnidaria, a free-swimming, ciliated larva formed after fertilization of the egg by sperm during sexual reporduction

Question 21

Polyp

Answer 21

One of the two Cnidarian body forms that is sessile and contains tentacles for obtaining food

Question 22

Sessile

Answer 22

Fixed in one place, immobile

Question 23

Medusa

Answer 23

One of the two Cnidarian body forms that is bell-shaped and free swimming, and possesses striated muscles which are derived from the epidermis and are not considered true muscles

Question 24

Hydrozoa

Answer 24

One of the classes of Cnidaria that includes organisms like Hydra, Obelia, Physalia (portuguese man-o-war)

Question 25

Scyphozoa

Answer 25

One of the classes of Cnidaria that includes organisms such as true jellyfishes

Question 26

Cubozoa

Answer 26

One of the classes of Cnidaria that includes organisms such as box jellyfish

Question 27

Anthozoa

Answer 27

One of the classes of Cnidaria that include the corals and sea anemones

Question 28

Zooxanthellae

Answer 28

Corals may obtain food from these photosynthetic algae that line the digestive cavity of corals

Question 29

Ctenophora

Answer 29

A phylum that includes organisms such as comb jellies

Question 30

Biradial symmetry

Answer 30

When the body can be divided into similar halves

Question 31

Colloblasts

Answer 31

Adhesive cells that Ctenophores use for trapping prey