Subphylum Crustaceans
Phylum Arthropoda Characteristics 67,000 species Lobsters, crabs, crayfish, shrimp
Also known as insects of the sea Mainly marine Only arthropods with two pairs of antennae Also have one pair of mandibles and two pairs of maxillae Have a pair of appendages on each body segment Most have between segments, but some canhave as many as 60 or more. Characteristics Three Tagmata:
Head Thorax Some crustaceans have fused the head and thoracic segments together to form the Cephalothorax Abdomen Some have a carapace-the dorsal cuticle of thehead may extend posteriorly and around thesides to cover the abdomen and thoracicsegments (ex. a lobster shell) Characteristics Bodies are covered with a secreted cuticlecomposed of chitin, protein, and calcareousmaterial The harder, heavy plates of larger crustaceans contain large portions of calcareous deposits Provides a hard protective covering Soft and thin at the joints Will have a telson, which will bear the anus Muscular System Striated muscles Flexors- draw a part toward the body
Extensors- extend a part outward Circulatory System Open circulatory system
No veins No separation of blood from interstitial fluid Hemolymph (blood) enters the dorsal heart(single-chambered sac of striated muscle) fromthe surrounding hemocoel (space in the coelomcontaining blood) The hemolymph will enter sinuses (spaces that serve as veins) Sinuses contain valves that prevent backflow into the heart The hemolymph will travel through the sinus to different organs such as the gills for oxygen and carbon dioxide exchange Circulatory System Hemolymph may be colorless, reddish or bluish
Hemocyanin (a copper-containing respiratorypigment) and Hemoglobin (an iron-containingpigment) may be present in the solution. This helps give the hemolymph the property of clotting, which prevents its loss in minor injuries. Respiratory System Use gills for respiration
Gills- delicate, featherlike projections with a very thin cuticle used for gas exchange Nervous System Have a well developed sense organ Advance eyes
Tactile hairs- cover mouthparts, cuticle andtelson Chemical senses for taste and smell can reside inreceptors on antennae, mouthparts etc. Reproduction Most crustaceans are dioecious Crustacean Evolution Classes Class Remipedia Class Cephalocarida Class Branchiopoda
Class Ostracoda Class Maxillopoda Class Malacostraca Class Remipedia Very small class of crustacea Live in caves
25-38 trunk segments Have swimming appendages Class Cephalocarida Small group- 9 species known 2-3mm long
Live in the bottom sediments of the intertidalzone of coasts No eyes No carapace No abdominal appendages True hermaphrodites Unique because they are the only arthropod thatdischarges both eggs and sperm into a commonduct Class Branchiopoda 10,000 species 3 orders:
Anostraca- fairy shrimp Notostraca- tadpole shrimp Diplostraca- water fleas Have phyllopodia legs that serve as chiefrespiratory organs Water fleas (cladocerans) will often produce onlyfemales in the summer, by parthenogensis (unisexualreproduction of a female) increasing the population. When conditions are unfavorable, some males will be produced, and eggs that must be fertilized are produced by normal meiosis Fertilized eggs are highly resistant to cold weather Class Ostracoda Enclosed in a bivalved carapace, encloses thebody but not the head Mussel shrimp or seed shrimp Development is gradual by metamorphosis Class Maxillopoda 6 subclasses: Subclass Mystacocarida
Subclass Copepoda Subclass Tantulocarida Subclass Branchiura Subclass Pentastomida Subclass Cirripedia Subclass Mystacocarida
Tiny crustaceans Live in interstitial water between sand grains ofmarine beaches Only 10 species Subclass Copepoda Small Lack carapace
Antennules are often longer than otherappendages and used for swimming Subclass Tantulocarida
12 species known No head appendages except for one pair ofantennae on sexual females Parathenogenetic Lose their abdomen and all thoracic limbs duringmetamorphosis Subclass Branchiura Small group of fish ectoparasites
Mouthparts are modifiedfor sucking- secondmaxillae have beenmodified as suction cups 5-10mm long Broad shield-like carapace Unsegmented abdomen Fish heavily infected withthese crustaceans can getinfections and die Subclass pentastomida
Tongue worms 130 species Wormlike parasites of the respiratorysystem of vertebrates Adults live mostly in lungs of reptiles (snakes, lizards and crocodiles Intermediate hosts may consist of fish or other reptiles, sometimes mammals 1-13cm Females are larger than males Females may produce several millioneggs Subclass Cirripedia Barnacles Enclosed in a shell of calcareous plates
Sessile as adults No abdomen Thoracic legs are long Nonparasitic barnacles arehermaphroditic Can have bivalve carapace Class Malacostraca 20,000 species Largest class with great diversity
3 subclasses, 14 orders and many suborders 4 orders we will discuss: Order Isopoda OrderAmphipoda Order Euphausiacea Order Decapoda Order Isopoda Truly terrestrial Dorsoventrally flattened
Lack a carapace Psuedotracheae-abdominal appendages bearinggills Can roll into tight ball for protection Ex. Pill bugs (Rolly Pollies) Order Amphipoda Lack carapace Compressed laterally
Appendages can be used for different functions Ex. One pair used for swimming, one pair for jumping Order Euphausia Krill 90 species 3-6cm long
Most arebioluminescent- containa photophore organwhich will produce light Food for many whaleand fish species Order Decopoda Lobsters, crabs, crayfishes and true shrimp
18,000 species Very diverse order 5 pairs of walking legs May have first pair of walking legs aremodified to form chelae (pinchers) Economically important because theyare used as food.