Ecdysozoa Flashcards
Describe priapulida
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
Describe kinorhyncha
Body in 13 segments
Chitinous cuticle
Invertible head
Head covered in cirlcets of spines
Describe nematoda
Spindle shaped
Well developed sensory system
Describe nematomorpha
Larvae are parasites of arthropods
Free living in fresh water as adults
Hair like body-thick cuticle
No digestive system/ no excretory system
Describe loricifera
Protective outer lorica
Invertible spiny head with oral stylets
What are panarthropods?
All arthropods
Describe panarthropods generally
Legs and claws
Ventral nervous system
Segmented body
What are the three divisions of panarthropoda?
Onychophora
Tardigrada
Arthropoda
What are onychophora?
Velvet worms
Describe the onychophora body plan?
Thin, flexible chitin cuticle
Segmented
Head is three segments
Describe onychophoran respiration
Tracheal system
Has spiracles
Trachea goes straight to organs
Describe onychophoran circulation
Has a haemocoel which is filled with haemolymph
Haemolymph carries only nutrients
Has a contractile heart
Describe onychophoran nervous system
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
Describe onychophoran digestion and excretion
Chitin lined foregut Dilated pharynx Narrow oesophagus Very short hindgut Each segment has a pair of metanephridia (coiled kidneys)
Describe onychophoran reproduction
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.
Describe onychophoran ecology
Specialised for life in leaf-litter
Papillae on head have slime glands
Some species form social groups which are female dominated
What are tardigrades?
Water bears
Describe the tardigrade body plan
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
Describe the tardigrade nervous system
Large dorsal brain with three median lobes and two lateral lobes Double ventral nerve cord Segmental ganglia Eye spots Hairs on body and legs
Describe tardigrade digestion and excretion
Liquid feeders
Stylets to pierce plant cells/animal prey
Describe tardigrade reproduction
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
Describe tardigarde ecology
Most of life spent in ‘tun’ which is extremely resistant
