Midterm II (Lophotrochozoa)

Question 1

Lophotrochozoa

Answer 1

Small
I. Phylum Rotifera
II. Phylum Acanthocephala
III. “Lopgophorates”
I. Phylum Ectoprocta (Bryozoa)
II. Phylum Brachiopoda
III. Phylum Phoronida
II. Phylum Nemertea

Question 2

All the small lophotrochozoans

Answer 2

• Gnathostomulida
• Micrognathozoa
• Rotifera
• Acanthocephala
• Cycliophora
• Gastrotricha
• Entoprocta
• Ectoprocta
• Brachiopoda
• Phoronida

Question 3

Phylum Rotifera

Answer 3

(“wheel bearers”)
- Most < 1 mm
- 2000+ species
- Marine, freshwater, brackish
- Ciliated crown = corona
- Pumping pharynx = mastex
- Many spp. without males (Parthenogenetic, diploid amictic egg)
- Other spp. with amictic egg -> female; and mictic (haploid) egg -> male if unfertilized
- Dormant fertilized eggs can withstand desiccation (drying out) for months
- NOT internally segmented (external only)

Question 4

Parthenogenetic

Answer 4

Clones itself with its own egg, all the genetic material in one egg

Question 5

Body forms indicative of lifestyle (Rotifera)

Answer 5

• Floating planktonic = globular
• Swimmers/creepers = wormlike
• Sessile = vase-like
• Colonial

Question 6

Phylum Acanthocephala

Answer 6

• Around 1100 spp., 2mm-1m
• Defining feature = retractable introverted spiny proboscis
• All parasitic in vertebrate (fish, birds) intestines
  
  • intermediate host (crustacean)
  • Absorb nutrients through epidermis - no digestive tract

Question 7

“Lophophorates”

Answer 7

• Ectoprocta, Brachiopodia, phoronida
  Lophophore = crown of cilia-covered tentacles
• Part/extension of the coelom: (eu)coelomates!
• For feeding and respiration
• U-shaped
• Mouth INSIDE, anus OUTSIDE
• Seen in Ectoprocta, Brachiopoda and Phoronida

Question 8

Phylum Ectoprocta (AKA Bryozoa)

Answer 8

(“outside anus; “moss animal”)
- 4000+ species; all aquatic
- Rich fossil record since Ordovician
(1500+ extinct)
- Most colonial (zooids!) in zoecium
(oblong calcareous chamber)
- most feeding forms, some polymorphism
- Invasive and fouling
- Medical compounds
- Bryostatin (cancer fighting) via bacterial symbionts

Question 9

Phylum Brachiopoda

Answer 9

(“arm + foot”; lampshells)
- Ancient (30,000 spp. of fossils; 300 spp. living)
- Articulata and Inarticulata
- 5-80 mm (some 30 cm!)
- 2 calcareous shells secreted by “mantle” (dorsal and ventral, unlike bivalve molluscs)
- Attached with pedicel (or pedicle, stalk), bottom-dwelling, shallow marine
- Adults not segmented, but larval stages show “some” repeated ectodermal and mesoderm tissues

Question 10

Phylum Phoronida

Answer 10

• Around 10 spp
• Few mm - 30 cm
• Wormlike, unsegemnted
• Leathery, chitinous tube (animal can withdraw completely inside)
  Unique actinotroch larvae
• In benthic substrate, shallow coastal temp seas