lecture 5 Invertebrates (non-arthropods): nematodes & echinoderms Flashcards
what does the phylum nematoda mean in latin
nemato = threadlike
what kind of symmetry do nematodes have
bilateral symmetry
what kind of bodies do nematodes have
cylindrical bodies with tapering ends
tubular, with mouth at head end starts the complete gut
what kind of coelomates are nematodes
pseudocoelomates
internal cavity but internal organs not surrounded by a mesoderm
what type of cuticle do nematodes have and how does this aid them
multi layered cubicle helps maintain high pressure inside (hydrostatic skelton)
what are the two life styles of nematodes
free living and parasites
where do free living nematodes live
found in all habitats
90% of animals on seabed, 80% of all individual animals
what do free living nematodes eat
in soil most eat bacteria and fungi(most species are microscopic)
some eat crops such as potato cyst nematodes
examples of parasitic nematodes
ascariasis
guinea worms
pinworms
what is elephantiasis
caused by infection with filariasis type nematodes
infects lymphatic system and causes swelling
what are the human stages in filariasis
mosquito takes a bite l3 larvae enters skin
adults in lymphatics produce sheathed microfilarae that migrate into lymph and blood channels
what are the mosquito stages in filariasis
mosquito takes a blood meal and ingest microfilariae
microfilariae shed sheaths penetrate mosquitos mid gut and migrate into thoracic muscles
l1 l3 larvae
migrate to head
mosquito takes a meal
what kind of sexual reproduction do nematodes have
separate sexes with sexual reproduction (internal fertilisation)
why is caenorhabditis elegans an important model for cell and developmental biology
first multicelular organism to have its genome sequenced
very rare case of androdioecous species
what does androdioecous mean
most are hermaphrodies but when stressed males exist (rare)
what does the phylum name echinodermata mean
echin = spiny derma = skin
what are some included echinoderms
sea lilies
sea urchins
starfish
sea cucumbers
what kind of symmetry do echinoderms have
bilateral in larvae
5 fold radial symmetry in adults
what kind of coelomates are echinoderms
coelomates
what does pentatomerous
radial body symmetry with five sides
what does the water-vascular system consist of
internal canals and external tube feet
what are the calcareous plates and spines
epidermis covering an endoskeleton
how do echinoderms reproduce
sexual reproduction with seperate sexes
what does the class crinoidea mean in latin
crino = lily
sea lilies and feather stars
what does the class asteroidea mean in latin
astero = star
starfish
what does the class ophiuroidea mean in latin
ophiuro = snake tail
brittle star
what does the class echinoidea mean in latin
echino = porcupine, hedgehog
seaa urchins and sand dollars
what does the class holothuroidea mean in latin
holothuro = kind of water polyp
what is special about nematodes external coat
it is thick and needs to be shed to grow
