ARTHROPODS http www iteachbio comMarine BiologyCrustacians mov SUBPHYLUM

ARTHROPODS

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SUBPHYLUM CRUSTACEA � Over 67, 000 species � Lobsters, crayfishes, shrimp, crabs, water fleas, copepods, barnacles � Primarily � Mostly � Only aquatic marine but some freshwater arthropods with 2 pairs of antennae � Mandible � 2 pairs of maxillae

LOBSTERS

CRAYFISH

SHRIMP

SHRIMP

CRABS

WATER FLEAS

WATER FLEAS

COPEPODS

COPEPODS

BARNACLES

BARNACLES

SUBPHYLUM CRUSTACEA � Major tagmata � Head, thorax, abdomen � Carapace �A hard outer covering or shell made of chitin

SUBPHYLUM CRUSTACEA � Form & Function � Appendages � Swimmerets � Endopod � (abdominal appendages) & exopod (inner & outer branches) Attached to one or more basal segments (protopod)

SUBPHYLUM CRUSTACEA General – � Majority are free swimming � Very important components of aquatic ecosystems � Have two pairs of antennae (only arthropods with these) � Most have between 16 and 20 segments � Compound eyes (detects motion) � Crabs & crayfish are on the ends of movable eyestalks

SUBPHYLUM CRUSTACEA � Ecdysis � (ekdysis = strip off) � Periodic shedding of old cuticle for a larger one � Feeding Habits � Suspension � Plankton, feeders detritus, bacteria � Predators � Larvae, worms, crustaceans, snails, fishes � Scavengers � Dead animals & plant matter

SUBPHYLUM CRUSTACEA CLASS BRANCHIOPODA � � Four orders are recognized: � � � branchia – gills, podos – foot Anostraca – fairy shrimp and brine shrimp Notostraca – tadpole shrimp (Triops) Conchostraca – clam shrimp (Lynceus) Cladocera – water fleas (Daphnia) Have reduced first antennae and second maxillae Legs are flattened and leaflike (phyllopodia) � chief respiratory organs

SUBPHYLUM CRUSTACEA CLASS MAXILLOPODA � include barnacles, copepods, ostracods, and related groups. Most are small � Most feed by means of their maxillae � Barnacles are an exception � Barnacles feed with thoracic appendages, but in a way that is unique among crustaceans. � � basic plan of 5 head and 10 trunk segments (6 thoracic and usually 4 abdominal) � The abdominal segments typically lack appendages; appendages elsewhere on the body are usually biramous. �

SUBPHYLUM CRUSTACEA CLASS MAXILLOPODA � Subclass Ostracoda � Enclosed in a bivalve carapace (resemble tiny clams; 0. 25 - 8 mm long) � Fusion of trunk segments; scavenge food, feed on detritus, or collect particles from water � Subclase � Small, Copepoda elongated, lack carapace and retain simple, median nauplius eye in adults � (kōpē – oar, podos – foot)

OSTRACODA COPEPODA

SUBPHYLUM CRUSTACEA CLASS MAXILLOPODA � Subclass Branchiura Branchia – gills, ura – tail � Primarily fish parasites (despite name, has no gills) � Broad, sheildlike carapace, compound eyes, 4 biramous thoracic appendages & short abdomen � � Subclass Cirripedia Cirrus – curl of hair, pedis – foot � Includes barnacles, as well as smaller orders of burrowing or parasitic forms � Barnacles are sessile as adults � � Attach � � to their substrate by stalk (gooseneck barnacles) directly (acorn barnacles) Typically, a carapace (mantle) surrounds their body and secretes a shell Head is reduced, abdomen is absent, and thoracic legs are long, many-jointed cirri with hairlike setae

SUBPHYLUM CRUSTACEA CLASS MALACOSTRACA � (malakos – soft, ostrakon – shell) � Largest Crustacae class � Trunk usually has 8 thoracic and 6 abdominal segments � each � Many with a pair of appendages marine &freshwater species � Includes krill, sow bugs, lobsters, crayfish, shrimp, and crabs

ISOPODA (CLASS MALACOSTRACA) � (isos – equal, podos – foot) � Commonly dorsoventrally flattened, lack a carapace, and have sessile compound eyes � Abdominal appendages bear gills � Common land forms are sow bugs (pill bugs)

AMPHIPODA (CLASS MALACOSTRACA) � (amphis – on both sides, podos – foot) � Resemble isopods in that members have no carapace and have sessile compound eyes � However, they are usually compressed laterally and their gills are in the thoracic position

EUPHAUSIACEA (CLASS MALACOSTRACA) � (eu – well, phausi – shining bright, acea – pertaining to) � Group of about 90 species � Important as oceanic plankton known as “krill” � Occur in great oceanic swarms � Eaten by baleen whales and many fish

KRILL

KRILL

KRILL

WHALE EATING KRILL

DECAPODA (CLASS MALACOSTRACA) � (deka – ten, podos – foot) � five pairs of walking legs � First is often modified to form pincers (chelae) � Lobsters, crayfish, shrimp, and crabs

LOBSTERS

CRAYFISH

CRABS