Chapter 30

Question 1

What is Kingdom Animalia in the tree of life?

Answer 1

Eukaryotic, Monophyletic clade, common ancestor with Choanoflagellates, closely related to Fungi,

Question 2

What are some characteristics of animals?

Answer 2

Multicellular, no cell walls (extracellular matrix), heterotrophic, get nutrition by ingestion, most animals (except sponges) have tissues

Question 3

What does the life cycle of an animal look like?

Answer 3

Most reproduce sexually (some can reproduce asexually), diploid cells (2N) are dominant (Only gametes are haploid), early embryonic development (cleavage, blastula stage, gastrulation, gastrula stage)

Question 4

What % of animals go through metamorphosis?

Answer 4

80%

Question 5

What are some characteristics of choanoflagellates?

Answer 5

Protists, single-celled or colonial, live in fresh & salt water

Question 6

What are some similarities and differences between Choanoflagellates and Phylum Porifera (sponges)?

Answer 6

Both feed the same way (filter-feeders), both are eukaryotes, and both are sessile (immobile). Choanoflagellates are single-celled or colonial protists, and sponges are multicellular animals.

Question 7

What are tissues?

Answer 7

Group of specialized cells that are separated from other tissues by membranous layers. They come from embryonic germ layers and are formed after gastrulation

Question 8

What are the classifications of animals based on tissues?

Answer 8

Metazoa - all animals, Parazoa - animals with no specialized tissues (sponges), Eumetazoa - have more than one type of tissue (all animals besides sponges)

Question 9

What is cleavage?

Answer 9

Mitotic (Mitosis) cell division without growth of the cell ball.

Question 10

What happens to the zygote during blastula development?

Answer 10

The zygote divides into smaller cells from one cell, to eight cells, to eventually the blastula.

Question 11

How does the gastrula form?

Answer 11

The blastula folds into the blastocoel (inside) and forms germ layers.

Question 12

What consists of the gastrula?

Answer 12

The blastopore (first opening in the gastrula), ectoderm (outside layer), endoderm (inside layer), and mesoderm.

Question 13

What are germ layers and what do they do?

Answer 13

Embryonic layers that develop into various tissues in the body. Ectoderm is the outer covering and develops into nervous tissue. Endoderm is the lining and develops into organs of the digestive tract. The mesoderm develops into the circulatory system, muscles, and some organs.

Question 14

What is diploblasty and what phylum is diploblastic?

Answer 14

Organisms that only have 2 germ layers (endoderm and ectoderm), are radially symmetrical, neural net, and have no coelom (acoelomate). Phylum Cnidaria are diploblastic.

Question 15

What are some characteristics of Phylum Cnidaria?

Answer 15

Jellyfish, coral, sea anemone, hydra, diploblastic, radial symmetry, and neural net.

Question 16

What are the types of body symmetry?

Answer 16

Radial symmetry - an organism that can be divided into two equal parts from multiple angles around the center point. Radially symmetric organisms are usually sessile or planktonic and experience the environment from all sides. Bilateral - an organism that can only be divided into two equal parts by only one line. Bilaterally symmetrical organisms have a central nervous system.

Question 17

What is the difference between a neural net and a central nervous system?

Answer 17

The neurons in a neural net are grouped together while a central nervous system has them all spread apart.

Question 18

What is triploblasty?

Answer 18

Has all 3 germ layers (ectoderm, endoderm, mesoderm) and a body cavity (coelomate)

Question 19

What is a coelom?

Answer 19

A body cavity - fluid-filled space that separates the digestive tract from outer body wall by the mesoderm

Question 20

What are the coelom types?

Answer 20

Coelomate (body cavity is completely lined with mesoderm), pseudocoelom (body cavity only has one layer of mesoderm; not fully covered), acoelomate (no body cavity; lost during evolution)

Question 21

Why do animals have a coelom (body cavity)?

Answer 21

The fluid in the body cavity acts as a cushion for organs and a skeleton in soft-bodied animals. It also provides more space for organs to grow and move independently from the outside of the body.

Question 22

What is the fate of the blastopore in protostomes and deuterostomes?

Answer 22

In protostomes, the blastopore (first hole in blastula) becomes the mouth, and the cleavage is spiral and determinate. In deuterostomes, the blastopore becomes the anus and the cleavage is radial and indeterminate.

Question 23

What are the “superphyla” of protostomes?

Answer 23

Lophotrochozoa - lophos means ciliated structure, Some have trochophore larvae before metamorphosis or a lophophore stage as an adult. Ecdysozoan animals secrete and shed external skeletons (exoskeletons) with growth.

Question 23

What does it mean to have determinate cleavage vs. indeterminate cleavage?

Answer 23

If a cell is removed from a 4-cell embryo, both cell balls die. It is missing important tissues because the future of the cell is already decided. Indeterminate cleavage means if a cell is removed, both cell balls will produce a complete organism and the cell future is more flexible.

Question 24

What is the Deuterostome superphylum?

Answer 24

Has all characteristics of triploblasts, are bilaterally symmetrical as larvae (adults are pentaradial). Includes phyla Echniodermata (sea stars, sea urchins, sea cucumbers) and Chordata (Lancelets, tunicates, vertebrates)

Question 25

Why is segmentation considered an advantage?

Answer 25

It has evolved independently at least 3 times in animals. It allows for specialization. Phylum Annelida, Arthropoda, and Chordata have segmentation.

Question 26

What are the 9 phyla in order from most to least diverse?

Answer 26

1. Arthropoda (spiders, crustaceans, insects)
2. Mollusca (snails, slugs, bivalves, cephal.)
3. Nematoda (roundworms)
4. Chordata (lancelet, tunicate, vertebrate)
5. Cnidaria (jellyfish, coral, anemone, hydra)
6. Annelida (segmented worms)
7. Echinodermata (sea stars, urchins)
8. Porifera (sponges)
9. Platyhelminthes (flatworms)

Question 27

What are the characteristics of phylum porifera (sponges)?

Answer 27

Multicellular (several types of cells), asymmetrical, loosely organized and “lack” tissues, 8000 species (mostly marine), larva are free swimming, adults are sessile

Question 28

How does phylum porifera develop?

Answer 28

Sponges do not produce gastrula like other animals, and they are parazoa because they do not have tissues.

Question 29

What does the structure of a mature sponge look like?

Answer 29

Body wall consists of 2 layers of cells, separated by a gelatinous region, Outer layer of epithelial cells, Middle gelatinous region called mesophyll which includes amoebocytes, Inner layer includes choanocytes

Question 30

What are some characteristics of Cnidarians?

Answer 30

10,000 species, mostly marine, diploblastic, radial symmetric, neural net, no coelom, gastrovascular cavity, polyp & medusa, etc. Specialized cells: cnidocytes (cell, contains nematocyst, an organelle that contains an injectable thread that causes a sting)