Lecture 6- Animal Diversity II

Question 1

Do basal animals have general or specific derived traits?

Answer 1

General (they lack more specific derived traits present in most animals)

Question 2

Phylum Porifera

Answer 2

“to have pores”- sponges
- Least complex animals
- Multicellular
- No symmetry, tissues, organs
- Basal metazoans

Osculum: open end
Spongocoel: central cavity

Water moves through, food filtered out. NOT a digestive cavity- digestion is intracellular
Basal Metazoans

Question 3

Choanocytes

Answer 3

“collar cells”- feeding cells of sponges (PHYLUM PORIFERA)
Very similar to choanoflagellates
Flagellated
Line spongocoel
Ingest bacteria, food particles

Question 4

Phylum Cnidaria

Answer 4

• True tissues
• Radial symmetry
• Diploblastic
  “Thin” (2 layers)
  Gastrovascular cavity
  Mostly marine
  Basal Eumetazoans

Question 5

Cnidocytes

Answer 5

Specialized stinging cells, unique to cnidaria
Mostly marine

Question 6

Cnidarians are basal ___________

Answer 6

Eumetazoans

Question 7

Porifera are basal __________

Answer 7

Metazoans

Question 8

Bilateria shared derived traits

Answer 8

Bilateral symmetry, triploblasty

Question 9

Nephrozoa shared derived traits

Answer 9

Coelom, excretory structures

Question 10

Eumetazoa shared derived traits

Answer 10

Tissues, symmetry

Question 11

Metazoa shared derived traits

Answer 11

ECM and multicellularity

Question 12

Deuterostomia shared derived traits

Answer 12

Deuterostome development (maybe), some with deuterostome development outside this group

Question 13

Protostomia shared derived traits

Answer 13

Protostome development (maybe), we aren’t sure which type of development is ancestral and which is derived

Question 14

Deuterostomia phyla

Answer 14

Echinodermata and chordata

Question 15

Spiralia Clade members

Answer 15

Platyhelminthes, Rotifera, Mollusca, Annelida

Question 16

Spiralia Clade derived traits

Answer 16

Entirely invertebrates, protostome development (named due to spiral cleavage). Grouped based on DNA

Question 17

Phylum Platyhelminthes

Answer 17

Dorsoventrally flattened
Acoelomate (derived trait)
Free-living
Parasitic
No body cavity
First in Protostomia and Spiralia Clade

Question 18

Phylum Rotifera

Answer 18

Within Spiralia Clade
Freshwater/marine, damp soil
Very small
Pseudocoelomates

Have corona: crown of cilia at anterior end

Question 19

Phylum Mollusca

Answer 19

Coelomates in Spiralia clade
3 main body parts: Mantle, visceral mass, and foot
Mantle: Thin sheet of tissue covering visceral mass, often secretes calcium carbonate shell
Visceral mass: Main body mass, contains viscera (internal organs)
Foot: Structure for locomotion

Radula: Belt of teeth in mouth area, scrapes up food (unique to mollusks)

3 Major Mollusk Clades
Gastropods- “stomach-foot”
Bivalves- “two-shells”
Cephalopods- “head-foot”

Question 20

Phylum Annelida

Answer 20

Last phyla of Spiralia Clade
“little rings”
Repeated segmentation
Body wall, coelom, many organs divided into segments
Marine, freshwater, soil

Question 21

Ecdysozoan Clade members

Answer 21

Nematoda, Arthropoda

Question 22

Ecdysozoa Shared Derived Traits

Answer 22

Ecdysis: Molting/shedding exoskeleton during growth (cicada)

Question 23

Phylum Nematoda

Answer 23

Within Ecdysozoan clade
Roundworms
Body covered in cuticle
Pseudocoelomates (derived)
Aquatic, soil, parasitic
Things like heartworm

Question 24

Phylum Arthropoda

Answer 24

Within Ecdysozoan Clade
“joint-foot”
Largest phylum by number of species (contains insects)
Coelomates
Often have deuterostome developmental traits

Question 25

Arthropod Structure + Derived Traits + costs

Answer 25

Segmented bodies
Often 3 parts- Head, thorax (legs & wings), abdomen

Derived: Jointed appendages
- Often modified, provide motility, allow for feeding, sensory

Derived: Exoskeleton
- Made of chitin and protein (sturdy)
- Jointed
- Covers entire body (protective shell, like grasshopper)
Functions of exoskeleton: Provides protection, prevents desiccation (drying), muscle attachment

Costs to exoskeleton:
- Limits growth (must molt to grow)
- Limits size