crustaceans

charactaristcs of crustaceans

body segmentation, biramous appendages, two pairs of antennae, exoskeleton, mouthparts, nauplius larva, open circlatory system, respiration, compound eyes

body segmentation (crustaceans)

divided into cephalothorax and abdomen

Biramous appendeges (crustaceans)

limbs typically branch into two parts

two pairs of antennae

used for sensing environment

exoskeleton

chitinous cuticle often reinforces with calcium carbonate; must be moulted during growth

mouth parts

three mouth parts, mandibles and two pairs of maxillae derived from head segments

open circulatory system

haemolymph flows through a haemocoel often using hemocyanin or haemoglobin to transport oxygen

respiration

typically through gills often lcoated on or near appendages

compound eyes

often stalked; capable of detecting form, size and sometimes colour

key features of copepods

small, body divided into cephalothorax, merasoma and abdomen, no abdominal appendagesl

life cycle of copepods

nauplius larva - 6 naupliar stages - 6 copepodite stages - adult

experiences ontogenetic vertical migration

feeding strats of copepods

omnivorous, ambush vs current feeders

ecological importance of copepods

form a critical part of food webs: transfer energy from primary producers to higher trophic levels

massive biomass contribution

body structure of decapods

cephalothorax and abdomen

cephalothorax covered by carapace

appendages of decapods

five pairs of legs first pair is often modified inot chelae for feeding, defence, competition

three pairs of maxillipeds

body form of barnacles

sessile as adults and permently attached to surfaces, body enclosed with a series of clacareous plates for protection

appendages barnacle

lack abdonminal appendages and typical walking legs adapted for feeding with cirri that capture plankton.

feeding strats for custaceans

filter feeding, deposit and suspention feeding, predation, herbivore, parasitism

filter feeding

barnacles use cirri to sweep plankton from water

copepods use antennules and mouthparts to filter or ambush-feed on phytoplankton

deposit feeding

isopods are detrivores feeding on organic matter in sediment

predation and scavenging

decapods often have chelae for grasping or breaking prey

herbivory

some amphipods and isopods graze on algae or biofilms

freshwater crustaceans consume decaying plant material

parasitism

some barnacles parasitise crabs by infiltrating their body and manipulating host behaviour and reproduction. parasitic copepods attach to fish gills or skin feeding on tissue and blood