Where are we? Ecdysozoa Deuterostomia Lophotrochozoa Nematoda Arthropoda Tardigrada Onychophora Annelida Mollusca Platyhelminthes Phylum Arthropoda Subphylum Crustacea Crustacea Terrestrial and aquatic All depths in marine, brackish, and freshwater > 67,000 described species, likely 5-10x that number no yet described Diverse form, size, and habitat 5 classes, 34 orders Characteristics Head = 5 segments, trunk divided into thorax and abdomen Carapace or cephalic shield Appendages multi-articulate; either uniramous or biramous Mandibles are modified limbs that function as jaws Gas exchange by diffusion across specialized surfaces Characteristics Excretion by nephridia Simple and compound eyes in at least one life cycle stage Compound eyes on stalk Gut with digestive cecae Nauplius larvae, either mixed or direct development 2 pairs of antennae Crustacean Bauplan Thorax anterior segments fused = cephalon Maxillipeds: additional mouthparts Number of segments in thorax varies Thorax appendages = pereopods swimming, walking, gas exchange, feeding, defense ultiarticulate and biramous Basic Crustacean Bauplan Abdomen Segments Number of segments used in ID Appendages = pleopods Biramous, flap-like swimming Culminate in telson Anus caudal rami w/uropods (last pair of abdominal appendages) forms tail fan Adult Crustacean Crustacean Bauplan Nauplius Larvae Single, median, simple eye 3 pairs of sectioned, functional limbs Become antennules, antennae, and mandibles Diagrams adult Crustacean diagram: http://www.enchantedlearning.com/subject s/invertebrates/crustacean/index.shtml Circulation Open circulatory system Dorsal ostiate heart Internal organs bathed in fluid Simple heart and vessels in most Sessile species no heart; pumping vessels Blood Variety of cell types Dissolved hemoglobin or hemocyanin Explosive cells release a clotting agent at injury sites Heart Shape Heart long and tubular; to postcephalic region Or, globular, box shape, in thorax; association with thoracic gills Gas Exchange Aquatic Small organisms = diffusion Concealed gills for protection, prevent dessication External gills Modified thoracic limbs Gills are thin; maximize gas exchange Most species beat gills to maintain flow Gas Exchange Terrestrial Cutaneous Respiration Membranes on legs of some species Gills Concealed Pseudotrachea Internal blind sacs to outside through small pores Air in sacs, gas exchange with blood Internal gills moist Water currents Hydraulic vacuum Filter feeding Feeding basket Passive Twirling antennae Direct manipulation Sand grazers or Sand lickers Predators Parasitism Water Currents Thoracic limbs for swimming and creating suspension feeding currents Water drawn into space Particles trapped by setae moved to food groove and toward head Hydraulic vacuum Mouth appendages = paddles Water containing food drawn into interlimb space Food particles are not filtered, but captured in small parcels of water Individual algal cells are captured this way Filter feeding Sessile crustaceans have feathery cirri to filter feed food up to one mm = detritus, bacteria, algae and various zooplankton Some can coil cirrus around large prey in a tentacle fashion Filter feeding in slow water Extend pairs of cirri like a fan Sweep rhythmically through water Filter feeding in fast water Allow water to run through filter video Passive feeding Use cirri to passively strain Burrow into sand with anterior facing upward Extend cirri to capture bacteria, protists and phytoplankton Antennae brush food towards mouth Twirl antennae Create spiraling currents that bring food toward mouth Food entangled in setae near base of mouth, brushed in Direct manipulation Manipulation by mouthparts, pereopods and subchelate anterior legs Sand grazers or Sand lickers Brush sand grains with setose mouthparts Select individual sand grain, rotate and tumble against mouthparts to remove organic material Predator Grab prey with chelae pereopods Tear, grind and shear with mouthparts Hunters or ambushers use raptorial subchelae to stab, club or smash prey Some hold prey in cage using endopods; others inject and suck out tissues Snapping Shrimp Use large cheliped to snap close: produces loud popping sound and “shock” wave Pressure wave stuns prey, pull into burrow Snapping Shrimp Video http://www.sciencemag.org/feature/data/1052273files/video.shl Digestive system Foregut Lined with cuticle that is continuous with exoskeleton, molted Short pharynx-esophagus, stomach Stomach = chambers for storage, grinding and sorting Midgut intestine Length varies with body shape and size, diet digestive ceca Hindgut Short, to anus Foregut functions transport food to midgut and/or processing by chemical digestion cardiac stomach = storage, bits are moved past gastric mill (sclerotized teeth for grinding) pyloric stomach = filter large particles midgut, hindgut and anus Excretion and Osmoregulation Ammonia by nephridia and gills nephridial excretory organs as antennal glands (green glands) or maxillary glands Inner blind end is coelomic remnant of nephridium = sacculus Sacculus Actively remove and secrete material from blood into excretory lumen metabolic waste removal and water and ion balance Other osmoregulation Thin areas of cuticle Gill surfaces terrestrial isopods: ammonia diffuses from the body as gas Nervous System and Sense Organs CNS Brain: three fused ganglia Protocerebrum Deutocerebrum Tritocerebrum Primitive nervous system = ladderlike Nervous System and Sense Organs variety of sensory receptors innervated setae or sensilla: contain mechanoreceptors and chemoreceptors Propioceptors Animals in Class Malacostraca: statocysts Nervous System and Sense Organs Two rhabdomeric photoreceptors: Median simple eyes Lateral compound eyes Most possess both, either simultaneously or during development Naupliar eye = primitive, secondarily lost Nervous System and Sense Organs Lateral compound eyes Lack visual acuity Discern shapes, patterns and movement Color vision in some Lacking in many taxa Nervous System and Sense Organs Underwater vision Problems with angular distribution of light, lower intensity, and narrow range of wavelengths than in air Solution: Mount eyes on stalks, increase information available to eyes. Increases field of view, and binocular range Nervous System and Sense Organs Complex Endocrine and Neurosecretory Systems Not well known Molting, chromatophore activity, and reproduction under hormonal and neurosecretory control Bioluminescence in several groups Reproduction And Development Reproduction Exploit virtually every life history scheme imaginable Usually dioecious Hermaphroditism in remipedes, cephalocarids, cirripedes, few decapods Parthenogenesis common among branchiopods and certain ostracods Reproduction And Development Reproduction Systems Gonads paired structures in trunk Pair of gonoducts from gonads to genital pores on trunk segment Male pair of penes, or single fused median penis Female include seminal receptacles Reproduction And Development Most crustacea copulate courtship behavior Pairing more or less permanent, or seasonal Reproduction And Development Fiddler crab example Males use cheliped waving to attract females, repel competing males Males produce sounds by stridulation, substratum thumping to attract mates Mating when male entices female into burrow Reproduction And Development Reproductive systems continued Sperm transferred either loose in seminal fluid or packaged in spermatophores Sperm deposited directly into oviduct or into seminal receptacle Sperm can be stored for long periods