1. Biology 320 Invertebrate Zoology Fall 2005 Chapter 19 – Phylum Arthropoda, Subphylum Crustacea

2. Introduction to Crustaceans 42,000 species 42,000 species Crabs, shrimps, lobsters, and barnacles Crabs, shrimps, lobsters, and barnacles Important ecologically Important ecologically ZooplanktonZooplankton Mainly marine, but some FW and a few terrestrial varieties Mainly marine, but some FW and a few terrestrial varieties Mandibulates, along with myriapods and insects Mandibulates, along with myriapods and insects Two pairs of antennae Two pairs of antennae

3. Body Form Two tagma in most Two tagma in most Two pairs of antennae Two pairs of antennae 1 st and 2 nd antennae1 st and 2 nd antennae Mandibles Mandibles Two pairs of maxillae Two pairs of maxillae 1 st and 2 nd maxillae1 st and 2 nd maxillae Lateral compound eyes Lateral compound eyes Often on eyestalksOften on eyestalks

4. Pereopods Pereopods Walking legsWalking legs Pleopods Pleopods SwimmeretsSwimmerets Uropods Uropods Make up tail finMake up tail fin Exoskeleton typically mineralized Exoskeleton typically mineralized CalcifiedCalcified

5. Nutrition and Digestive System Many strategies; feed on suspended particles, detritus, carrion, plants and/or animals Many strategies; feed on suspended particles, detritus, carrion, plants and/or animals Possess several mouthparts Possess several mouthparts Usually have gnathobasesUsually have gnathobases Coxae of appendages forms a food grooveCoxae of appendages forms a food groove Many use a structure called a setal comb to filter feed Many use a structure called a setal comb to filter feed Often located on feeding appendagesOften located on feeding appendages

6. Most have J – shaped gut Most have J – shaped gut Often have a grinding stomach called a gastric mill Often have a grinding stomach called a gastric mill Midgut has digestive ceca termed the hepatopancreas Midgut has digestive ceca termed the hepatopancreas Intestines form and remove wastes Intestines form and remove wastes Also reclaim waterAlso reclaim water Anus located at base of telson Anus located at base of telson

7. Other Organ Systems Small species don’t require complex organ systems Small species don’t require complex organ systems Hemal Hemal Typical of arthropodsTypical of arthropods Hemocyanin or hemoglobin dissolved in plasmaHemocyanin or hemoglobin dissolved in plasma Respiratory Respiratory Gills located in branchial chamberGills located in branchial chamber Inhalant and exhalant chambersInhalant and exhalant chambers Gill bailer (scaphognathite) ventilatesGill bailer (scaphognathite) ventilates Many strategies for cleaning gills and removing sediment from branchial chamberMany strategies for cleaning gills and removing sediment from branchial chamber

8. Excretory system Excretory system Paired saccate nephridiaPaired saccate nephridia Located in segment with 2 nd antennae or 2 nd maxillae Located in segment with 2 nd antennae or 2 nd maxillae Called antennal, maxillary, or green glands Called antennal, maxillary, or green glands Nephridiopores open near 2 nd antennae/maxillae Nephridiopores open near 2 nd antennae/maxillae Most marine species are osmoconformers Most marine species are osmoconformers Freshwater species are osmoregulators Freshwater species are osmoregulators Ammonotelic, so nitrogen diffuses across gills Ammonotelic, so nitrogen diffuses across gills

9. Nervous system is typical of arthropods Nervous system is typical of arthropods EyesEyes Often compound with as many as 14,000 ommatidia Often compound with as many as 14,000 ommatidia Often at the end of a movable eyestalk, which greatly increases the field of view Often at the end of a movable eyestalk, which greatly increases the field of view Some can distinguish colors Some can distinguish colors Many use chromatophores to match color of surroundingsMany use chromatophores to match color of surroundings Statocysts and chemosensorsStatocysts and chemosensors Often associated with antennae Often associated with antennae Animals frequently clean their antennae Animals frequently clean their antennae

10. Reproduction All but barnacles are gonochoric All but barnacles are gonochoric Usually copulation with internal fertilization Usually copulation with internal fertilization Penis or gonopods transfer sperm Penis or gonopods transfer sperm Appendages such as 2 nd antennae are often used to grasp female Appendages such as 2 nd antennae are often used to grasp female

11. Sometimes males cannot mate with females until after she molts Sometimes males cannot mate with females until after she molts Most brood eggs attached to appendages or in brood chambers Most brood eggs attached to appendages or in brood chambers Direct or indirect (nauplius larva) development Direct or indirect (nauplius larva) development

12. Class Anostraca Fairy shrimp and brine shrimp (sea monkeys) Fairy shrimp and brine shrimp (sea monkeys) Live in ephemeral pools Live in ephemeral pools Typically salineTypically saline Lack fishesLack fishes 15 – 30 mm, but some grow as large as 10 cm 15 – 30 mm, but some grow as large as 10 cm Lack carapace Lack carapace Sexually dimorphic Sexually dimorphic Males have large 2 nd antennae for grasping femalesMales have large 2 nd antennae for grasping females

13. Stalked compound eyes Stalked compound eyes Possess setal combs for suspension feeding Possess setal combs for suspension feeding Swim upside down Swim upside down Many tolerate a wide range of salinities Many tolerate a wide range of salinities Sperm transfer is direct Sperm transfer is direct Internal fertilizationInternal fertilization

14. Class Phyllopoda 800 species 800 species Inhabit freshwater habitats that are similar to those of anostracans Inhabit freshwater habitats that are similar to those of anostracans Two main types Two main types Large - tadpole shrimpsLarge - tadpole shrimps Small - water fleasSmall - water fleas

15. Tadpole Shrimps Triops is most famous genus Triops is most famous genus Ten species altogetherTen species altogether Enormous shield-like carapace covers most of the animal Enormous shield-like carapace covers most of the animal Most are small, but some reach 10 cm in length Most are small, but some reach 10 cm in length Amazing physiology Amazing physiology Dr. Carl Reiber’s lab has conducted research using Triops as a modelDr. Carl Reiber’s lab has conducted research using Triops as a model Survive in hypoxia and anoxiaSurvive in hypoxia and anoxia Hemoglobin subunit recruitment Hemoglobin subunit recruitment Produce two types of eggsProduce two types of eggs Summer eggs- thin shelled and hatch rapidly Summer eggs- thin shelled and hatch rapidly Winter eggs - undergo diapause Winter eggs - undergo diapause

16. Water Fleas Also called cladocerans Also called cladocerans Daphnia is most famous genusDaphnia is most famous genus Often live in ponds and lakes where they make up a large portion of FW zooplankton community Often live in ponds and lakes where they make up a large portion of FW zooplankton community Swim using enlarged 2 nd antennae as oars Swim using enlarged 2 nd antennae as oars Undergo cycles of parthenogenesis and bisexual reproduction Undergo cycles of parthenogenesis and bisexual reproduction

17. Typically brood eggs Typically brood eggs Two types of eggs produced Two types of eggs produced Undergo cyclomorphosis Undergo cyclomorphosis Seasonal changes in morphologySeasonal changes in morphology Head shape, spines, neck teeth producedHead shape, spines, neck teeth produced Evidence suggests these changes are inducible responsesEvidence suggests these changes are inducible responses

18. Class Malacostraca Many important orders of crustaceans Many important orders of crustaceans Crabs, crayfish, and shrimps Crabs, crayfish, and shrimps 23,000 species 23,000 species Tagmatization is standardized Tagmatization is standardized

19. Order Stomatopoda 300 species of mantis shrimps 300 species of mantis shrimps Predators of fish, crabs, shrimps, and molluscs Predators of fish, crabs, shrimps, and molluscs Raptorial claws are extended and retracted rapidly to capture prey Raptorial claws are extended and retracted rapidly to capture prey Best developed compound eyes of any crustacean Best developed compound eyes of any crustacean Some even have depth perceptionSome even have depth perception

20. 5 cm – 36 cm long 5 cm – 36 cm long Can be brightly colored Can be brightly colored Many live in burrows Many live in burrows Often pair up with one mate for life Often pair up with one mate for life Squilla is most famous genus Squilla is most famous genus

21. Order Decapoda 10,000 species of shrimps, crayfishes, lobsters, and crabs 10,000 species of shrimps, crayfishes, lobsters, and crabs Important ecologically and economically Important ecologically and economically All have 10 legs, hence the name All have 10 legs, hence the name

22. Shrimp-like Decapods Laterally compressed Laterally compressed Thin flexible exoskeleton (uncalcified) Thin flexible exoskeleton (uncalcified) Muscular abdomen that can be used for escaping (tail flip) Muscular abdomen that can be used for escaping (tail flip) Large pleopods for swimming Large pleopods for swimming Benthic Benthic

23. Penaeus is a common genus Penaeus is a common genus Snapping shrimp Snapping shrimp SynalpheusSynalpheus Has one extremely large chelipedHas one extremely large cheliped One movable finger is cockedOne movable finger is cocked When released the force generated can stun prey or crack a clam shellWhen released the force generated can stun prey or crack a clam shell Also makes a loud noiseAlso makes a loud noise

24. Lobster-like Decapods More dorsoventrally flattened More dorsoventrally flattened Heavier legs Heavier legs Chelipeds Chelipeds Muscular abdomen Muscular abdomen Tail flipsTail flips Small pleopodsSmall pleopods Homarus and Procambarus are famous genera Homarus and Procambarus are famous genera

25. Crab-like Decapods Most dorsoventrally compressed of the three groups Most dorsoventrally compressed of the three groups Abdomen is greatly reduced Abdomen is greatly reduced Hermit crabs have a large abdomen that is soft and is housed in a shellHermit crabs have a large abdomen that is soft and is housed in a shell Periodically need to find larger shellsPeriodically need to find larger shells Typically walk sideways Typically walk sideways Some like Callinectes can swim Some like Callinectes can swim

26. Eggs brooded between the cephalothorax and abdomen Eggs brooded between the cephalothorax and abdomen Types of crabs: Types of crabs: Alaskan kingAlaskan king Probably the largest crab Probably the largest crab Mole crabsMole crabs Lack chelipeds Lack chelipeds Burrow in sand Burrow in sand

27. Japanese spider crab Japanese spider crab Greatest leg span of any arthropodGreatest leg span of any arthropod Decorator crabs Decorator crabs Have hooked setaeHave hooked setae Attach things to its exoskeletonAttach things to its exoskeleton Aids in protection and camouflageAids in protection and camouflage Dungeness crab Dungeness crab Cancer magisterCancer magister Probably the most popular food crabProbably the most popular food crab

28. Freshwater Decapods Crayfish Crayfish The most successful with 400 species, worldwideThe most successful with 400 species, worldwide Many live under stones and some burrowMany live under stones and some burrow Procambarus is an invasive species in Western USProcambarus is an invasive species in Western US Shrimps Shrimps Most are tropicalMost are tropical A few species in the USA few species in the US Crabs Crabs Usually must return to the sea at some point to release larvaeUsually must return to the sea at some point to release larvae Chinese mitten (or river) crab is an invasive in CAChinese mitten (or river) crab is an invasive in CA

29. Terrestrial Crabs Adapted for life on land Adapted for life on land Morphological adaptationsMorphological adaptations Gills converted into a modified lung Gills converted into a modified lung Uricotelic Uricotelic Behavioral “adaptations”Behavioral “adaptations” Typically live near oceans or in other high humidity habitats Typically live near oceans or in other high humidity habitats Visit water to wet body and respiratory surfaces Visit water to wet body and respiratory surfaces Typically burrow and are nocturnal Typically burrow and are nocturnal Some brood embryos on land and make mass migrations to release larvae Some brood embryos on land and make mass migrations to release larvae

30. Terrestrial hermit crabs (Coenobita) Terrestrial hermit crabs (Coenobita) Coconut crabs (Birgus) Coconut crabs (Birgus) Climb trees and open coconuts, which they eatClimb trees and open coconuts, which they eat Drink sea waterDrink sea water Can reach one meter in lengthCan reach one meter in length Some can lift 28 kgSome can lift 28 kg Christmas Island red crabs Christmas Island red crabs Make mass migrations from forests to the sea every year to mateMake mass migrations from forests to the sea every year to mate

31. Fiddler crabs are considered semi- terrestrial Fiddler crabs are considered semi- terrestrial Uca lives on sand or mud beaches or in mangrove swamps Uca lives on sand or mud beaches or in mangrove swamps Emerge from burrows when the tide is out Emerge from burrows when the tide is out ForagingForaging MatingMating FightingFighting Dependent on tide to bring new food and remove wastes Dependent on tide to bring new food and remove wastes

33. The Decapod Hemal System Heart is not tubular Heart is not tubular Rectangular with three pairs of ostiaRectangular with three pairs of ostia Well developed vasculature Well developed vasculature Seven major arteries leaving heartSeven major arteries leaving heart McGaw and Reiber have studied many parameters of decapod circulation McGaw and Reiber have studied many parameters of decapod circulation Circulation takes around 40 sec in large species Circulation takes around 40 sec in large species Hemocyanin transports around 90% of oxygen Hemocyanin transports around 90% of oxygen

34. Neurosecretory Organs of Decapods Eyestalks are the most important neurosecretory organs Eyestalks are the most important neurosecretory organs Hormones synthesized in neuron cell bodies of eyestalk control: Hormones synthesized in neuron cell bodies of eyestalk control: MoltingMolting ChromatophoresChromatophores ReproductionReproduction Sinus gland in eyestalk stores and releases hormones into blood Sinus gland in eyestalk stores and releases hormones into blood There are a few endocrine organs outside of nervous system, but these are under nervous control There are a few endocrine organs outside of nervous system, but these are under nervous control Y-organY-organ Secretes ecdysone Secretes ecdysone Located in anterior cephalothorax Located in anterior cephalothorax

35. Chromatophores Located in connective tissue, deep to the epidermis Located in connective tissue, deep to the epidermis Color change is apparent in areas where the cuticle is thin or transparent Color change is apparent in areas where the cuticle is thin or transparent Used for: Used for: Thermoregulation – blanching in fiddler crabsThermoregulation – blanching in fiddler crabs Concealment – many shrimps change color to match surroundingsConcealment – many shrimps change color to match surroundings Astaxanthin is a carotenoid pigment found in decapods Astaxanthin is a carotenoid pigment found in decapods Is blue in live animals, because it is bound with a proteinIs blue in live animals, because it is bound with a protein Boiling denatures the protein and the animal turns redBoiling denatures the protein and the animal turns red

36. Decapod Reproduction Copulation Copulation Hermit crabs have to partially exit shellHermit crabs have to partially exit shell Sperm transfer is indirect Sperm transfer is indirect Spermatophore extruded from penes, onto gonopodsSpermatophore extruded from penes, onto gonopods Transferred by gonopodsTransferred by gonopods Most anterior pair of pleopods, that are modified Most anterior pair of pleopods, that are modified

37. Aquatic species attract each other using pheromones Aquatic species attract each other using pheromones Tactile cues are also importantTactile cues are also important Visual and sometimes auditory cues are important to terrestrial species Visual and sometimes auditory cues are important to terrestrial species Combat between male fiddler crabsCombat between male fiddler crabs Egg mass is known as a sponge, and is brooded on pleopods Egg mass is known as a sponge, and is brooded on pleopods

38. Autotomy Limbs occasionally get autotomized (removed) Limbs occasionally get autotomized (removed) PredatorsPredators Self amputationSelf amputation Little bleeding Little bleeding Limb bud forms Limb bud forms New limb regenerates insideNew limb regenerates inside Limb bud unfolds during next molt Limb bud unfolds during next molt Removing a limb bud delays molting until a new bud forms and limb is regeneratedRemoving a limb bud delays molting until a new bud forms and limb is regenerated

39. Class Malacostraca, Order Euphausiacea 85 species of krill 85 species of krill Pelagic, shrimp-like animals found throughout oceans Pelagic, shrimp-like animals found throughout oceans Small (about 3 cm long), but found in enormous densities Small (about 3 cm long), but found in enormous densities 60,000 / m 360,000 / m 3 Chief food for many marine animals Chief food for many marine animals Blue whale may consume four tons per dayBlue whale may consume four tons per day Bioluminescence functions in schooling and courtship behaviors Bioluminescence functions in schooling and courtship behaviors Can rapidly molt and leave exuvia behind as decoys Can rapidly molt and leave exuvia behind as decoys

40. Order Amphipoda 6000 species of scuds 6000 species of scuds Gammarus is most famous genusGammarus is most famous genus Small (5 – 15 mm) Small (5 – 15 mm) Giant Pacific scuds can reach 28 cm and live 5300 m deepGiant Pacific scuds can reach 28 cm and live 5300 m deep Some FW species, and some semi-terrestrial such as beach hoppers Some FW species, and some semi-terrestrial such as beach hoppers Can leap many times body lengthCan leap many times body length Laterally compressed Laterally compressed

41. Order Isopoda 4000 species 4000 species Mostly marine Mostly marine Pill bugs (wood lice) are the most successful terrestrial crustaceans Pill bugs (wood lice) are the most successful terrestrial crustaceans Most are 5 -15 mm, but the deep sea isopod (Bathynomus) reaches 42 cm Most are 5 -15 mm, but the deep sea isopod (Bathynomus) reaches 42 cm

42. Dorsoventrally compressed Dorsoventrally compressed Nutritional strategies Nutritional strategies Some bore into woodSome bore into wood Some are carnivorousSome are carnivorous Some parasitize fishesSome parasitize fishes Have enrollment muscles (pill bugs) Have enrollment muscles (pill bugs) Terrestrial species specialized structures to collect water and channel it to gills Terrestrial species specialized structures to collect water and channel it to gills

43. Class Copepoda 12,000 species 12,000 species Most marine, but FW varieties dominate zooplankton communities Most marine, but FW varieties dominate zooplankton communities Some are parasitic Some are parasitic Free-living varieties are small (1 - 17 mm), but some parasites reach 25 cm Free-living varieties are small (1 - 17 mm), but some parasites reach 25 cm Long first antennae Long first antennae Used by males to grasp femalesUsed by males to grasp females Usually branch 90° angles, relative to longitudinal axisUsually branch 90° angles, relative to longitudinal axis

44. Possess a median nauplius eye Possess a median nauplius eye Form oil droplets for buoyancy, which can lead to petroleum deposits Form oil droplets for buoyancy, which can lead to petroleum deposits Some undergo DMV of around 300 m Some undergo DMV of around 300 m One researcher figured out that this is the greatest movement of biomass on the planetOne researcher figured out that this is the greatest movement of biomass on the planet Famous genera: Famous genera: CyclopsCyclops TisbeTisbe Swarm on small fish and eat at their fins Swarm on small fish and eat at their fins After fish is immobilized, it is devoured After fish is immobilized, it is devoured

45. Class Cirripedia Barnacles Barnacles Secrete and inhabit a rigid calcareous shell that is capable of growth Secrete and inhabit a rigid calcareous shell that is capable of growth Sessile animals that encrust on rocks, timber, ships, and even whales Sessile animals that encrust on rocks, timber, ships, and even whales Fouling ability is amazing Fouling ability is amazing May reduce speed and fuel efficiency of a ship by 30%May reduce speed and fuel efficiency of a ship by 30% Abundant intertidally, and may be found in distinct patters of zonation Abundant intertidally, and may be found in distinct patters of zonation Due to interspecific competitionDue to interspecific competition

46. Larvae settle and cements to substrate using glands on its head Larvae settle and cements to substrate using glands on its head Ventral aspect is upVentral aspect is up Six pairs of cirri on thorax are used for filter feedingSix pairs of cirri on thorax are used for filter feeding Hermaphroditic Hermaphroditic Highly extensible penis deposits sperm in a neighboring barnacleHighly extensible penis deposits sperm in a neighboring barnacle

47. Calcareous shell is secreted by exoskeleton Calcareous shell is secreted by exoskeleton There are two pairs of ventral, movable calcareous plates that form an operculum There are two pairs of ventral, movable calcareous plates that form an operculum Scuta – anterior platesScuta – anterior plates Terga – posterior platesTerga – posterior plates Muscles control aperture diameter Muscles control aperture diameter Ecdysis occurs but calcareous shell / plates aren’t shed Ecdysis occurs but calcareous shell / plates aren’t shed Shell is added on to with new secretions Shell is added on to with new secretions

48. Diversity Diversity Acorn barnaclesAcorn barnacles Balanus Balanus Those on West coast of South America can be 23 cm high, 8 cm wide, and are eaten locally Those on West coast of South America can be 23 cm high, 8 cm wide, and are eaten locally Stalked barnaclesStalked barnacles Have a peduncle and capitulum Have a peduncle and capitulum Lepas can grow to 75 cm in height Lepas can grow to 75 cm in height

49. Some do not produce shells Some do not produce shells Bore into rocksBore into rocks Others parasitize crabs Others parasitize crabs Barnacles alter crab’s behavior, physiology, and anatomyBarnacles alter crab’s behavior, physiology, and anatomy Molting suppressed Molting suppressed Reproduction suppressed, in fact most are sterilized Reproduction suppressed, in fact most are sterilized Male crabs become feminized and develop a larger female abdomen, into which barnacle places its own brood pouch Male crabs become feminized and develop a larger female abdomen, into which barnacle places its own brood pouch Betters suits the barnacle’s needsBetters suits the barnacle’s needs

50. Class Ostracoda 6000 species of seed shrimps that resemble miniature clams 6000 species of seed shrimps that resemble miniature clams Have a bivalved carapaceHave a bivalved carapace 0.25 – 25 mm (Gigantocypris) 0.25 – 25 mm (Gigantocypris) Some have cephalic silk glands and spinnerets that secrete silk threads used for: Some have cephalic silk glands and spinnerets that secrete silk threads used for: DraglinesDraglines Building shelters for moltingBuilding shelters for molting

51. Carapace is an extension of head Carapace is an extension of head Is shed with each moltIs shed with each molt Some have bioluminescence Some have bioluminescence Bluish lightBluish light Flashed for periods of 1 to 2 secondsFlashed for periods of 1 to 2 seconds Used to attract matesUsed to attract mates

52. Class Branchiura 200 species of fish lice 200 species of fish lice Ectoparasites of marine and FW fishes, and tadpoles Ectoparasites of marine and FW fishes, and tadpoles 5 – 30 mm in length 5 – 30 mm in length Structural adaptations for attaching to host Structural adaptations for attaching to host First antennae have clawsFirst antennae have claws Mandibles are toothedMandibles are toothed First maxillae are suckersFirst maxillae are suckers Produce digestive enzymes to erode host tissue, and feed on blood and mucus Produce digestive enzymes to erode host tissue, and feed on blood and mucus Infestations in fish farms can eradicate entire populations Infestations in fish farms can eradicate entire populations