Tardigrades and Onychophores

Question 1

Tardigrada
describe the body plan of a tardigrade

Answer 1

• 4 segments total (2 lopopods and 4 ganglia on each)
• oldest segment = anterior
• only coelom is at gonads
• hemocoelic body
• no circulatory structures (diffusion instead)
• has a ventral nerve cord
• legs have claw structures at the end
• molting cuticle

Question 2

Tardigrada
how has the cuticle of a tardigrade been motified and what effects does this have?

Answer 2

• cuticle is thick and rigid (chitin/protein)
• no cilia
• lost typical functions like gas exchange, suspension feeding, swimming

Question 3

Tardigrada
what adaptation to waste excretion do tardigrades have?

Answer 3

traded nephridia for Malpighian tubules (food waste and nitrgenous waste exits together)

Question 4

Tardigrada
what structure do tardigrades use to feed?

Answer 4

stylets (pierces cell walls to suck up contents)

Question 5

Tardigrada
what is a tun?

Answer 5

period of dehydrated dormancy during harsh conditions

Question 6

Tardigrada
what are hulls?

Answer 6

cuticle covering tardigrade embryos

Question 7

Onychophora
what are the common name of onychophores?

Answer 7

velvet worms

Question 8

Onychophora
describe the body plan of velvet worms

Answer 8

• molted cuticle that lacks cilia and is flexible
• coeloms at gonads and nephridia
• antennae
• unjointed lopopods
• simple eyes
• 3 head segments + one segment for every pair of appendages

Question 9

Onychophora
what unique method do velvet worms use to hunt?

Answer 9

• slime gland on third head segment
• shoots out slime to trap prey
• pierces prey with fanged jaws and dissolves internal contents