Lecture 25

Question 1

Evolution of Animals: When did animals begin to evolve? From what did they evolve?

Answer 1

700 years ago from single-celled Eukaryotes.

Question 2

What is a Eukaryote:

Answer 2

A cell with a nuclear wall with membrane-bound organelles.

Question 3

When did the Cambrian Explosion Happen:

Answer 3

535 to 525 million years ago. Gave rise to the common large forms of present-day animals.

Question 4

What was the first animal group during the Cambrian Explosion?

Answer 4

Sponges.

Question 5

What is the scientific group (phylum) for the sponges?

Answer 5

Porifera.

Question 6

How do Sponges eat and how?

Answer 6

Sponges are filter feeders, they capture food through particles suspended in water.

Question 7

How does the water move through the sponge for filter feeding?

Answer 7

Water moves through the body’s pores, through the central cavity, and out through the opening at the top.

Question 8

Sponges do not have “true tissues” what does this mean?

Answer 8

Instead of “true tissues” its has groups of cells that function as one unit, rather than having specialized cells that function as a singular unit. A true tissue has an ectoderm or and endoderm. A sponge doesn’t have a true gastrula which during embryogenosis when the embryo of the egg is formed during fetilization.

Question 9

Sponges: Parts of the sponge?

Answer 9

Choanocyte: Cells that surround the central cavity. Create a current that draws water through the pores and forces water out of its cavity during filter feeding.

Pores: Water enters through its pores in the body wall of the sponge. The cells in the wall are separated by a gelatinous matrix, similar to the skin of mammals.

Amoebyctes: Cells that transport nutrients to other cells in the sponge body.

Question 10

What are tissues:

Answer 10

Collections of specialized cells that act as a functional unit, isolated from other tissues. Formed during embryogenesis from the germ layers to develop organs and tissues.

Question 11

Types of Tissues:

Answer 11

Ectodderm, Mesoderm, Endoderm

Question 12

What is ectoderm:

Answer 12

The outer germ layer gives rise to the outer covering and the central nervous system.

Question 13

What is the mesoderm:

Answer 13

Fills the space between the ectoderm and the endoderm and gives rise to muscles and most other organs.

Question 14

What is the endoderm:

Answer 14

The innermost germ layer gives rise to the digestive tract and the lining of internal organs.

Question 15

What are Cnidarians:

Answer 15

Cnidarians arose about 680 million years ago and have diversified into both sessile and motile forms, including hydrozoans, jellies, and sea anemones.

Question 16

What do Cnidarians have in common with all other animals?

Answer 16

True tissues. Every animal apart from sponges and a few other groups have tissues.

Question 17

Three common types of Cnidarians:

Answer 17

Hydrozoa, Scyphozoa, and Anthozoa.

Question 18

What are Jellyfish?

Answer 18

Scyphozoa, are bioluminescent, and some stun their prey with nematocysts, specialized cells, located on their tentacles.

Question 19

Types of Symmetry:

Answer 19

Bilateral Symmetry, Radial Symmetry, and Asymmetrical.

Question 20

Radial Animals Typically:

Answer 20

Drift or weakly swimming (planktonic), or are attached to substrate (sessile).

Question 21

Bilateral Animals Typically:

Answer 21

Move actively the CNS to enable coordinated movement.

Question 22

Phylum: Platyhelminthes

Answer 22

The simplest animals are bilaterally symmetrical, and triploblastic (3 cell layers) and lack a body cavity.

Question 23

Most bilaterians possess a body cavity (coelom). Which is used for?

Answer 23

Suspending organs with fluid to cushion them, and enable internal organs to move independently of the body wall.
Allows internal organs to move independently of the body wall.

Question 24

Types of Coelom:

Answer 24

Coelomate, Psuedocolelomate (fake, meaning not having a body cavity not dervied from the mesoderve instead being drived from the blastocoel) , and Acoelomate (no fluid between wall and mesoderve).

Question 25

Phylum: Nematodes and Rotifera: What makes these groups different?

Answer 25

Embryonic Development within the animal.

Question 26

What is the protosome?

Answer 26

“First-mouth”

Question 27

What is the deuterostome?

Answer 27

“Second-mouth”

Question 28

Phylum: Mollusca: What are its traits?

Answer 28

The second largest animal phylum, has a true coelom, and a free-swimming larval stage.

Question 29

What is segmentation:

Answer 29

The division of the body into a series of smaller segments.

Question 30

What are the advantages of segmentation:

Answer 30

Other sections might be able to perform the function of a damaged section.
Segments can be more independent - flexible and capable of complex movement.

Question 31

Phylum: Annelida: What are Annelids?

Answer 31

Annelids are segmented worms that live primarily in marine or freshwater habitats.

Question 32

Annelida Traits:

Answer 32

Exhibit organ system level organization.
Their body is segmented.
They respire through their body surface.
They have a well-developed circulatory and digestive system.
Regeneration is a very common characteristic of the Annelids.

Question 33

Phylum: Arthropoda: How many species

Answer 33

1,000,000 species known currently.

Question 34

Arthropoda: What are they?

Answer 34

Arthropods have segmented exoskeleton and jointed appendages.

Question 35

What groups are part of phylum arthropoda?

Answer 35

Insects, millipedes, crabs, and arachnids.

Question 36

Arthropod Origins: Where are they found and why.

Answer 36

Members of Arthropoda are found nearly in all habitats of the biosphere and their body plan attributes to their success.