arthropod introduction Flashcards
lecture 11 - Dave Bilton
what is an anthropod?
share with annelids:
- through gut
- ventral nerve cord with segmented ganglia
- dorsal circulatory system
differ from annelids
- external skeleton (moulted)
- paired jointed limbs (on each segment )
annelids
phylum of invertebrate worm
anthropod skeleton
composed of chitin (polysaccharide), proteins and mineral salts (esp. in the crustacea) such as calcium carbonate
anthropod cuticle
arthropod cuticle is a multifunctional coat that defines and stabilises the shape of the body, appendages and internal organs
cuticle has to be shed periodically to allow growth (size vs biomass)
- occurs through hormonally-mediated process known as ecdysis
ecdysis
the process of shedding the old skin (in reptiles) or casting off the outer cuticle (in insects and other arthropods).
anthropod diversity
most diverse phylum of living organisms
> 1,100,000 described species (85% animal diversity)
estimates of the real number of extant species span 3 orders of magnitude
- 30-50+ million species
shifting baseline syndrome
a gradual change in the accepted norms for the condition of the natural environment due to lack of past information or lack of experience of past conditions
anthropoda : ecological range
occur in all environments on earth
- deep ocean : vent shrimps - alvinocaridae
- high mountains : many nebria ground beetles and snow flea boreus
- forest canopies : stag beetle - lucanidae
- glaciers : tardigrades ( can undergo cryptobiosis )
- caves : cave beetle (leiodidae)
cryptobiosis
a state of extreme inactivity in response to adverse environmental conditions
sacculina
barnacle parasite of crabs. larva settles then the parasite spreads through the host -egg- containing sacs appear externally
pentastomida
(arthropod parasite)
lungs and nasal passages of vertebrates
