Ecdysozoa

Question 1

Describe priapulida

Answer 1

Burrow in slime
Warty cuticle
Superficially segmented cuticle
Body divided into presoma (barrel shaped and can be retracted into the trunk and is spiny) and trunk

Question 2

Describe kinorhyncha

Answer 2

Body in 13 segments
Chitinous cuticle
Invertible head
Head covered in cirlcets of spines

Question 3

Describe nematoda

Answer 3

Spindle shaped

Well developed sensory system

Question 4

Describe nematomorpha

Answer 4

Larvae are parasites of arthropods
Free living in fresh water as adults
Hair like body-thick cuticle
No digestive system/ no excretory system

Question 5

Describe loricifera

Answer 5

Protective outer lorica

Invertible spiny head with oral stylets

Question 6

What are panarthropods?

Answer 6

All arthropods

Question 7

Describe panarthropods generally

Answer 7

Legs and claws
Ventral nervous system
Segmented body

Question 8

What are the three divisions of panarthropoda?

Answer 8

Onychophora
Tardigrada
Arthropoda

Question 9

What are onychophora?

Answer 9

Velvet worms

Question 10

Describe the onychophora body plan?

Answer 10

Thin, flexible chitin cuticle
Segmented
Head is three segments

Question 11

Describe onychophoran respiration

Answer 11

Tracheal system
Has spiracles
Trachea goes straight to organs

Question 12

Describe onychophoran circulation

Answer 12

Has a haemocoel which is filled with haemolymph
Haemolymph carries only nutrients
Has a contractile heart

Question 13

Describe onychophoran nervous system

Answer 13

Has paired ventral nerve cords which are connected by commisural nerves
Has not true ganglia
Antennae are sense organs
Has simple eyes at the base or antennae

Question 14

Describe onychophoran digestion and excretion

Answer 14

Chitin lined foregut
Dilated pharynx 
Narrow oesophagus 
Very short hindgut 
Each segment has a pair of metanephridia (coiled kidneys)

Question 15

Describe onychophoran reproduction

Answer 15

Females are larger than males
Indirect internal fertilisation
Males produce spermatophores which are either inserted into the female’s gonopores, placed on female’s body so cuticle collapses, or placed on male’s own head.

Question 16

Describe onychophoran ecology

Answer 16

Specialised for life in leaf-litter
Papillae on head have slime glands
Some species form social groups which are female dominated

Question 17

What are tardigrades?

Answer 17

Water bears

Question 18

Describe the tardigrade body plan

Answer 18

Four body segments 
Each segment has paired appendages 
Missing trunk gene so mostly head 
Exoskeleton divided into segments 
No respiratory system- just diffusion
Has haemocoel- hydrostatic skeleton

Question 19

Describe the tardigrade nervous system

Answer 19

Large dorsal brain with three median lobes and two lateral lobes
Double ventral nerve cord
Segmental ganglia 
Eye spots
Hairs on body and legs

Question 20

Describe tardigrade digestion and excretion

Answer 20

Liquid feeders

Stylets to pierce plant cells/animal prey

Question 21

Describe tardigrade reproduction

Answer 21

Some species lack males
Females moult
Males inject sperm into old cuticle before female emerges
Eggs fertilised in space between old cuticle and female
Old cuticle becomes an egg case

Question 22

Describe tardigarde ecology

Answer 22

Most of life spent in ‘tun’ which is extremely resistant