subphylum crustaceans
DESCRIPTION
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 16-20 segments, but some can have as many as 60 or more.TRANSCRIPT
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.