Week 3

Question 1

Steps of boring sponge (feeding/boring)

Answer 1

1. Chemical dissolution
2. Chipping
3. Release into environment

Question 2

Porifera reproduction

Answer 2

Asexual = budding and regeneration (gemmules)
Sexual = germ cells in mesohyl (sperm phagocystosed by choanocytes and delivered to egg = lecithrotrophic larvae)

Question 3

Characteristics/apomorphies of Placozoa

Answer 3

• No neurons/muscles
• No basement membrane
• Fiber syncytium
• Shiny spheres (only dorsal epithelium; defense mechanism)
• Ciliary gliding
• Gland cells

Question 4

What are eumetazoa?

Answer 4

(not in online trees, only traditional textbooks)
All animals except sponges and placozoa

Question 5

Characteristics of eumetazoa

Answer 5

• Body symmetry (radial and bilaterial)
• Epithelial tissue
• Gut, muscle, nerves

Question 6

Where are apical cells located

Answer 6

Exterior side (epithelia)

Question 7

Where are basal cells located

Answer 7

Interior side (epithelia)

Question 8

Where are PARACELLULAR transport junction/channels located

Answer 8

Between cells

Question 9

Where are INTRACELLULAR transport junction/channels located

Answer 9

Through cells

Question 10

Cnidaria apomorphies

Answer 10

• Stinging cells (cnidocytes)
• Polyp adult and planula larva
• Nerve nets
• Longitudinal and circular muscle
• Endodermal gonads
• Circular mitochondrial DNA

Question 11

Anthozoa apomorphies

Answer 11

(Anthozoa = group in cnidaria)
- Polyps with pharynx
- Siphonoglyph
- Septa
- Septal filaments
(- No medusa stage)

Question 12

3 major groups in Medusozoa

Answer 12

Scyphozoa
Cubozoa
Hydrozoa

Question 13

Scyphozoa apomorphies

Answer 13

Scyphozoa -> medusozoa -> cnidaria)
- Strobilation (transverse fission)
- Strobila produced ephyra
- Medusa have rhopalia (statocyst, mechanoreceptor, photoreceptor)
- Gastric filaments (nematocysts and digestive cells)

Question 14

Cubozoa apomorphies

Answer 14

Cubozoa -> medusozoa -> cnidaria
- small polyps lacking septa
- tentacles on pedalia at 4 corners of bell
- 4 rhopalia with ocelli
- velarium
- well developed eyes with lenses (rhopalium) = lense, cornea, retina; can look inwards and outwards

Question 15

Hydrozoa apomorphies

Answer 15

Hydrozoa -> medusozoa -> cnidaria
- Medusa with velum
- Endodermal cnidae absent
- Gamete spawned directly from gonads to external environment
- Nerve rings with gap junctions

Question 16

Medusozoa apomorphies

Answer 16

• Medusa stage
• Linear mitochondrial DNA

Question 17

Nematocysts (what is it + function)

Answer 17

“Stingers” in cnidocytes
Mechanosensory for release/injection of toxins
- Prey capture and defense

Question 18

What are (cnidaria/porifera?) skeletons made of

Answer 18

Mostly calcium carbonate; some have chitin; polyps have hydrostatic skeleton

Question 19

Ctenophora apormorphies

Answer 19

• Biradial symmetry
• Comb rows
• Ctenes
• Basal group (despite specialization)
• Aboral organ (ciliated groove connected/controls comb rows; helps orientation)
• Tentilla (branches off tentacles) containing collocytes

Question 20

Collocyte function (+group)

Answer 20

Secret sticky substance for prey capture in Ctenophora

Question 21

Bilateria apomorphies

Answer 21

• Bilateral symmetry
• Anterior posterior
• Dorsal and ventral sides
• Cephalization
• Filtration excretory organs

Question 22

Protosomia development (hint: blastula)

Answer 22

• Blastopore becomes mouth
• Schizocoely (where coloem forms)

Question 23

Deuterostomia development (hint: blastula)

Answer 23

• Blastopore becomes anus
• Gastrulation (1D embryo becomes multilayered/dimensional blastula)

Question 24

Steps of indirect metamorphic life cycle (symmetry in development)

Answer 24

1. Cleavage
2. Gastrulation
3. Larval development
4. Metamorphosis
5. Adult/reproduction
6. Fertilization
   (cycles)

Question 25

Components of cnidaria nervous system

Answer 25

• Sensory, motor, internuerons
• 2 nerve nets (epidermal and gastrodermal)
• Ganglia