MAR 250 Exam 2

Platyhelminthes

Flatworms
-bilateral symmetry
-3 tissue layers
-central nervous system
-incomplete digestive tract(gut with no anus)
-no body cavity
-no circulatory system
-hermaphroditic

Class Turbellaria

free living flatworm (mostly non parasitic)

Class Monogenea

monogenetic flukes (parasitic)

Class Trematoda

digenetic or aspidogastrean flukes

Class Cestoda

tapeworms (parasitic)

Nemertea

Ribbon Worms
-proboscis
-reduced body cavity
-circulatory system
-many are poisonous
-separate mouth and anus

Nematoda

Round Worms
-free living and parasitic
-only longitudinal muscles
-pseudoceolom
-circular
-cuticle out case

Chaetognatha

Arrow Worms
-no retractable anterior
-caudal fin
ciliary fans
grasping spines

Sipuncula

Peanut Worms
-retractable anterior
-benthic
brain and central nerve cord

Annelida

Segmented Worms
-metamerism
-ceolom
-locomotion via longitudinal and circular muscles

Prostomium

head (front of mouth)

Peristomium

first segment (surrounds mouth)

Class Polychaeta

sand worms, tube worms, clam worms

Class Clitellata

earthworms

Types of Feeders

-suspension feeder (serpulids)
-filter feeder (feather duster worm)
-deposit feeder (lugworm)

Annelid Circulation

-closed circulatory system
-two major blood vessels (dorsal and ventral)
-5 muscular hearts
-blood also moved by contraction of locomotion muscles

Annelid Asexual Reproduction

-fragmentation in polychaeta and dodecaceria
-transverse fission, some oligochaeta
unknown in Hirudinoidea

Polychaeta Sexual Reproduction

-most male or female (dioecious)
-epitoky (no specific reproductive organs)

Earthworm Sexual Reproduction

-hermaphroditic
-clitellum secrete cocoon
-external fertilization
-no larva stage

Leech Sexual Reproduction

-hermaphroditic
-sperm fertilizes egg still in body
-internal fertilization
-no larva stage

Mollusca

-huge size range
-bilateral symmetry
-unsegmented
-protostomes
-complete gut
-large complex nephridia
-mantle
-foot
-radula

Mollusc suspension feeding

-use gills (ctenidia)
-food particles are trapped in mucus on gills and transported to mouth

Mollusc Reproduction

-dioecious or hermaphroditic
-sometimes free spawning, external fertilization, indirect development, or internal fertilization

Class Bivalvia

Bivalves

Class Monoplacophora

snails and slugs with spirally coiled shell

Class Cephalopoda

Squids and octopuses

Class Scaphophora

tusk shells

Class Aplacophora

marine veriform molluscs

Class Polyplacophora

Chitons

Bivalves

-two shells
-mostly sessile filter feeders
-usually separate sexes
-no head or radula
-held together by a hinge ligament
-umbo (oldest part of the shell and growth occurs in rings around it)
-mantle modified to siphons (used for burrowing or pump water through for gas exchange)

Class Gastropoda

-largest class
-torsion (rearranges organs and brings them together)
-herbivors, omnivores, and carnivores

Gastropod and Bivalve circulation

-open circulatory system
-heart with atria
-hemocoel

Cephalopoda

-octopus, squid, and cuttlefish
-ink sacs
-the earliest had straight cone shaped shells
-later examples had coiled shells similar to nautilus
-cuttlefish have a small curved shell, completely enclosed by the mantle
-use tentacles and beaks to eat

Squid/Octopus Circulation

-closed circulatory system
-3 hearts (arterial systemic and 2 venous branchial)

Squid/Octopus Communication

-visual signals
-movement of body and arms (color changes by chromatophores)

Squid/Octopus Reproduction

-sexes are separate
-juveniles = eggs
-one arm of male is modified to remove a spermatophore from mantle cavity and inserts it into female

Subphylum Triolobitomorpha

Trilobites

Subphylum Crustacea

Crabs, lobsters, shrimp

Subphylum Hexapoda

Insects

Subphylum Myriapoda

Centipedes and millipedes

Subphylum cheliceriformes

Horseshoe crabs and spiders

Phylum Arthropoda

-bilateral symmetry
-segmented body
-well developed exoskeleton
-each true segment with appendages
-cephalon with compound eyes
-reduced coelom
-annelid like nervous system

Lophaphorate

-share a feeding organ
-shaped like a loop and ciliated

Phylum Phoronida

-worm like, living in tubes of sand grains
-circular or horseshoe shaped lophophore

Phylum Ectoprocta

-bryozoans
-some are encrusting, others form small fan or tree shaped colonies
-suspension feeders

Phylum Brachiopoda

-lamp shells
-two shells enclosing body
-coiled lophophore

Phylum Echinodermata

-radial symmetry
-endoskeleton
-can regenerate lost body parts
-coelomic water vascular system with tube feet
-complete gut
-no excretory organs
-nervous system is decentralized

Class Crinoidea

sea lilies and feather stars
-5+ arms for suspension feeding
-mostly deep but many inhabit coral reefs
-some use mucus net to aid in food capture
-have cup shaped with upward reaching arms that catch zooplankton on specialized tube feet

Class Asteroidea

sea stars
-locomotion from tube feet
-central disc in center of body surrounded by 5 arms
-internal organs extend through entire body
-calcium carbonate plates are loosely embedded in spiny skin making them slightly flexible
-mostly carnivores
-hollow gills cover the body

Class Ophiuroidea

brittle stars
-central flat disc surrounded by thin, flexible arms
-internal organs are restricted to the central disc
-tube feet with suckers used for feeding on detritus
-no anus

Class Echinoidea

sea urchins and sand dollars
-conspicuous, movable spines
-rigid plates fused into a solid test
-move with tube feet
-mouth on the bottom, anus on top of body
-aristotles lantern

Class Holothuroidea

sea cucumbers
-mouth and anus on opposite ends
-5 rows of tube feet restricted to one side
-radial symmetry
-skin embedded with calcareous spicules
-no spines
-deposit feeders

Echinoderm water vascular system

-opens to exterior through madreporite
-tube feet
-regulated by hydraulic pressure
-gas exchange, feeding, locomotion

Evisceration

expulsion of the internal organs when disturbed internal organs regenerate back

Hemichordates

share some features with chordates including
-pharyngeal gill slits
-hollow dorsal nerve cord
-ex. acorn worms
-dioecious

Chordates

-2 invertebrate groups (Tunicates and Lancelets)
-vertebrates (fish, amphibians, reptiles, birds, mammals)
-one hollow, dorsal nerve cord
-notochord
-gill slits along anterior half of pharynx
-tail extending beyond anus

Subphylum Urochordata

Tunicates
-only larvae have chordate characteristics
-sessile filter feeders
-tunic: thick outer cover of sac like body
-Salps: planktonic adults, transparent body

Class Ascidacia

Sea squirts
-characterized by an outer tunic made of polysaccharide cellulose
-colonial
-strictly marine
-all sessile
-most diverse class of tunicates

Class Larvacea

-rarely exceeding 5mm
-planktonic
-tadpole shaped
-feed mainly on tiny phytoplankton and bacteria
-anus opens directly to the outside into the path of water flowing out of the excurrent siphon
-construct a house of mucus

Class Thaliaca

Salps
-planktonic
-transparent
-filter large volumes of water for feeding
-some are colonial

Subphylum Cephalochordata

Lancelets
-possess all chordate features as an adult
-fish like body except the absence of a backbone
-small
-filter feeders in shallow, soft sediments

Class Amphibia

few marine species
-marine toad
-crab eating frog

Class Reptilia

-ectotherms
-lower metabolic rate
-require less food
-can get cold stunned
-thick, scaly skin
-kidneys excrete uric acid
-nearly 4 chambered heart

Sea snakes

-most toxic venom of any snake
-lay eggs on shore or viviparous

Sea turtles

-swim with forelimbs
-eat sea grass, sponges, jellyfish
-travel long distances to breed

Sea Turtle Life Cycle

-females return to same beach they were born
-hatchlings crawl toward shoreline using cues of light and magnetic field of the earth
-predation on hatchlings very high

Class Aves

-no teeth, horny beak instead
-forelimbs = wings
-have feathers
-most use oils from uropygial glands to waterproof feathers
-bony skeleton
-all breed on land
-feed in ocean

Class Aves Metabolism

-endothermic, homeothermic
-benefits: active in all temperatures
-costs: eat more, higher O2 demand

Class Aves Heat Conservation

-body streamlined (reduces drag and surface area)
-locomotory muscles in trunk (heat near core)
-feathers (oils repel water)
-countercurrent heat exchange from extremities

Class Aves Respiration

lungs
-have one way air flow
-air sacs

Class Aves Circulation

-true 4 chambered heart (oxygenated blood separate from deoxygenated blood)
-more hemoglobin and myglobin
-larger blood volume
-bradycardia: heart rate slows dramatically to decrease metabolic rate
-vasoconstriction: reduces blood supply to most organs to save oxygen for necessary organs

Class Aves Reproduction

-sexual maturity late in long lived marine species
-chromosomal sex determination
-internal fertilization
-oviparous, gonochoristic
-many single egg clutch
-amniotic egg: shell protect embry
-biparental care
-most monogamous

Class Aves Excretion

-uric acid: small water loss
-nasal glands: concentrate sodium chloride drips down nasal passage to opening on beak

Class Aves Feeding

-predatory or scavengers
-fly long distances for surface food
-diving and underwater swimming

Class Aves Sensory System

-vision: keen, large eyes, more photoreceptors
-olfactory: diminished in most
-auditory: well developed

Order Sphenisciformes

penguins
-flightless
-forelimbs = flippers
-only birds with blubber layer
-colonial breeders
-most antarctic
-dive to 100m
-huddle to keep warm

Order Procellariiformes

petrels, albatrosses, shearwaters
-tubenoses
-hooked bill
-long, narrow wings
-glide
-breed colonially
-detect dimetholsulfate produced by phytoplankton
-eat zooplankton, inverts, and fish

Order Pelecaniformes

pelicans, boobies, gannets, cormorants
-totipalmate: all 4 toes webbed
-gular sac
-heavy bodies
-plunge dive for swim to catch fish

Order Charadriiformes

gulls, terns, skuas, auks
-breed in large colonies
-short, stubby wings
-short legs
-short stout bills
-prey on small fish and zooplankton

Phylum Mammalia

-pelage (hair)
-mammary glands
-endothermic, homeothermic
-internal fertilization
-4 chambered heart
-teeth modified according to diet
-eutherian (placental) mammals

Family Ursidae

polar bear
-white hair
-longer body and head
-smaller ears and tail
-large feet
-teeth modified for seal diet
-only marine mammal with multiple offspring

Family Mustelidae

sea and marine otter
-smallest but larger than river forms
-aquatic birth and lactation
-teeth modified for crushing (sea urchins)
-extremely dense fur
-very high metabolic rate
-live entire life in water

Family Otariidae

sea lions and fur seals
-birth on land
-pup births followed by copulation
-after birth, females alternate time with pup and feeding trips to sea
-male maintain well defined territoreies
-males 2-5 times larger than females by weight

Family Phocidae

seals
-traditional breeding sites
-birth on land or ice
-generally, females stay with pup for entire lactation
-mating at/near weaning
-males larger in some species

Family Odobenidae

walrus
-tusks
-thick, creased skin
-terrestrial locomotion
-benthic invertebrate prey
-2 years lactation

Order Cetacea

whales, dolphins, and porpoises
-large body size
-fusiform body shape
-hindlimbs absent, forelimbs modified to fins
-vertical tail movement
-carnivorous
loss of hair

Suborder Mysticeti

baleen whales
-2 blowholes on top of head
-annual migration for poles to equator

Suborder Odontoceti

toothed whales, dolphins, and porpoises
-one blowhole
-shape and size of teeth varies
-large variation in body size
-some have beak
-generally live in social groups

Order Sirenia

dugongs and manatees
-herbivorous
-fusiform body (no hindlimbs)
-large expanded tail
-warm, shallow water
-little hair
-thoracic mammary glands

Diving in Marine Mammals

-most feed near the surface
-most maximum dive 500m in 20min
-thermoregulate
-conserve oxygen
-increased oxygen storage in blood
-more myoglobin in muscles
-don't usually exceed aerobic dive limit
-larger body size, more storage, longer dive

Feeding in Baleen Whales

-rights: ram feeding, skimming
-rorquals: gulp, then strain
-gray: suction feeding
-right whales: copepods, some krill
-rorquals: large zooplankton, some schooling fish
-gray whales: benthic invertebrates

Dispersal

undirected, one way movement

Migration

long distance movement of individuals, usually on a seasonal basis

Mechanisms of migration

-sunlight
-magnetic fields
-currents

Diadromous

move between estuaries and the open sea

Anadromous

fish live as adults in salt water, spawn in freshwater (more common in higher latitiudes)

Catadromous

fish live as adults in freshwater, spawn in salt water (more common in lower latitudes)

Natal homing

returning to the place you were born

Diel vertical migration

planktonic organisms move towards surface at night and descend during day

Lecithotrophic larvae

-depend on nourishment from yolk
-no feeding structures
-drift for hours to days