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Non - Amniotes
- Jawless fishes (formerly Agnatha)
- - Hagfish: Myxinoidea
- - Lamprey: Petromyzontoidea
- Chondrichthyes:
- - Sharks
- - Rays
- - Ratfishes (Chimera)
- Osteichtyes (Bony fish)
- - Actinopterygians (ray fin) > 27,000 species
- - Sarcopterygians (lobe fin or fleshy-fin)
- Amphibians
- - Salamanders (urodela)
- - Frogs (anura)
- - Caecilians (gymnophiona)
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Actinopterygians
- Ray finned fish
- Chondrostei - Primitive fish
- - Sturgeon
- - paddlefish
- - bichir
- Neopterygii - modern ray finned fish
- - Gar
- - Bowfin - Amia calva
- - Teleostei - Virtually all fish species
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Surinam Toad
- Pipa Pipa
- South American - Amazon Region
- Unique parental care -
- - Fertilized eggs are embedded in back of mother
- - sink into pockets and covered with skin
- - eggs develop through the tadpole stage in the back of the moter
- - Hatch as small frogs (froglets)
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Amniotes
- Sauropsid Amniotes
- - Testudinia - Turtles
- - Lepidosauria - Tuatara, Lizards, Snakes
- - Crocodilia - alligators and crocodiles
- - Birds (aves)
- --dinosaur lineage that evolved flight in the Mesozoic Era
- Synapsid Aminotes
- - Mammals
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Synapsid Aminotes
- Mammalia
- - Placental mammals (also eutheria)
- - Marsupials (also metatheria)
- - Monotermes (also prototheria)
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Placental mammals (Eutheria) include
- Ungulares (mammals with hoofs)
- - Perissodactlys (odd number of toes) example - horse
- - Artiodactlys (even number of toes) example - pigs, deer and cattle
- Rodentia (rodents)
- - beaver
- - mouse
- - rat
- Lagomorpha
- - rabbit
- - hares
- - pika
- Lipotyphla
- - Shrews
- - moles
- - hedgehogs
- Chiroptera
- - bats
- Cetacea
- - whales
- - dolphins
- Carnivora
- - foxes
- - wolves
- - dogs
- - cats
- - weasels
- - raccoon
- - seals
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Pleistocene Extinction
- 2.5 million - 11,700
- Encompassed many large, terrestrial mammals "Pleistocene megafauna"
- example - mammoths and mastodons
- Human expansion - hunting? disease? climate change? asteroid impact? or some combination?
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On what islands did many species become extinct more recently with the arrival of humans -
- New Zeland : Maori arrived 800 years ago
- Hawaii, Ploynesians arrived 1,700 years ago
- Madagascar arrivals began 2,000 years ago
- and through exploration fron the 15th - 20th centuries
- example -
- - Mauritis (the dodo in mid 17th century)
- - Hawaii (even more species)
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Discuss the 2010 Internation Union for the Conservation of Nature list and their strategies -
- 1 in 5 vertebrate species listed as threatened
- 25% of mammal species
- 41% of amphibian
- Strategies -
- - Capitive breeding to maintain genetic diversity
- - elimintating pollutants
- -- DDT used as an insecticide post WW2, banned in the USA in 1972, especially damaging to bird reproduction (thin eggshells
- --Bald eagle almost extinct in US and Canada in 1960s, since 2007 no longer threatened
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Phylum Chordata
- Chordates
- Shared Features (some appear only during embryonic development)
- Notochord
- Dorsal, hollow nerve cord
- Muscular, postanal tail
- Pharynxwith gill slits
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Vertebrate Features (500 mya, Cambrian Period)
- Carnium (skull) surrounding a large head, complex sensory equipment
- Muscular Pharynx
- Mobility
- Vertebrae (of bone or cartilage) form around notochord/nerve cord
- - in hagfish (jawless fish), no vertebrae
- - In lamprey, only rudimentrary vertebrae made of cartilage
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Bone
- Mineralized tissue
- Other mineralized tissue includes enamel and dentine of teeth
- Two types of bone -
- - dermal bone formed in the skin used to form an exoskeleton, now just the skull
- - Endochondral bone formed inside cartilage
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Vertebrate Features - Innovations
- Cranium (skull) with large brain and complex sense organs
- Muscular pharynx
- Gill (pharyngeal) arches of cartilage
- Gills primarily for respiration
- Muscles pump water over gills and through pharynx
- Muscular gut (peristalsis)
- Ventral heart pumps blood (3 chambers initially)
- closed circulatory system (capillaries)
- Blood transport gases (red blood cells with hemoglobin) - O2 from gills to organs, CO2 back to gills
- Kidney keeps body more dilute than seawater
- Mobility (in most fishes contacting muscles on either side of stiff notochord/vertebral column)
- Bone - Demal bone vs. endochondral bone
- Vertebrae (of bone or cartilage) form around notochord/nerve cord
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Extant Jawlss Vertebrates
- Formerly Agnatha
- Hagfish - Myxinoidea
- - .5m long, "eel skin" wallets
- - lack vertebrae - probably not ancestral to jawed fishes
- - deep water, eyes degenerate
- - scavenge dead or dying vertebrates
- - body fluid same dilution as seawater
- Lampreys - Petromyzontoidea
- - tiny vertebral structures
- - mostly parasitic, max 1 meter
- - tidal ventilation - draw water in and out through gills
- - larvae spend years as burrowing filter feeders
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Sea Lamprey
- Petromyzon marinus
- native to Lake Ontario, could not go up Niagra Falls
- Threaten Great Lakes fisheries
- Arrived in Lake Erie in 1921
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Early vertebrates were probably ocean dwellers -
- - fossils of early vertebrates are all marine
- - comparative - all chordates are marine
- -- all non-vertebrate chordates and hagfish have body fluid same as seawater
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Ostracoderm
- Early Jawless Vertebrate
- Shell Skin
- 10-50cm long
- Diversified by 400mya
- Small plates of dermal bone form head shield
- Odontodes, dentine covered with enamloid (formed within the skin)
- Probably ate small, soft prey
- Most had a dorsal (i.e. back) fin
- Co-existed with gnathostomes (jawed fishes) for 50 million years
- Extinction in Late Devonian along with many marine invertebrates
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Gnathostomes
- Jawed Vertebrates
- Know from about 450 mya
- Allowed new diets, like herbivory - increase in size
- Can use jaw to grasp things - offspring, mates, pebbles, grass (new behaviors)
- Jaw formed from Mandibular gill arch
- Also have paired pectoral and pelvic fins (later to become limbs)
- Evolution of teeth - arise from dermal bone, probably initially in the pharynx
- two olfactory tracts leading to two nostrils (nares = holes in skull)
- Vertebrae evolve from bony arches surrounding the nerve cord and notochord
- ribs
- lateral line canal - organs that snese vibration in water (lost in some adult amphibians and in aminotes)
- Muscles in the eye for focus
- Pancreas, stomach and spleen
- Large cerebellum(in hindbrain)
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Gnathostome Taxa
- By the Devonian 416 mya -
- - Placoderms (extinct) - armored, probably ancestral
- - Acanthodians (extinct) - similar to osteichthyians
- - Chondrichthyans (extant)
- - Osteichthyans (extant) - endochondrial bone, swim bladder/lung, Operculum (gill cover)
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Placoderm
- "plate skin"
- Sperate head and body plates
- Widely varied morphology
- Some like armored catfish
- Includes 10 meter - long Dunkleosteus
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Acanthodians
- Spines
- Many paired fins
- Sister taxa to modern bony fishes
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Challenges to life in water
- need to maintain stable interior environment
- ions cross freely between body and water
- is the water more or less salty than the body? - different strategies for dealing
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Vertebrate Kidney
- Removes salt, water and waste from the blood
- Freshwater teleosts - do not drink, get extra salts from food
- -most exchange of H2O and ions is in the gills (ions actively pumped in, also diffused out)
- -Kidney reabsorb ions, produce lots of urine
- Freshwater amphibians - also don't drink
- - Actively take up ions from water through skin
- Marine Teleosts - drink seawater
- - Most exchange of H2O and ions is in gills (ions actively pumped out)
- - low amounts of urine, but very concentrated
- - ions = sodium, chloride
- Marine Cartilaginous Fish - do not drink
- - H2O, ions diffuse across gills
- - low permeability to salt
- - maintian internal concentration close to seawater, slightly more salty (=hyperosmodal)
- - retain nitrogen compounds
- - secrete saly fluid to rid extra ions
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Chondrichthyes
- Sharks
- Ratfish (Chimera)
- Manta Ray
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Ratfish
- Chimera
- Single gill opening
- up to 1.5m long
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Manta Ray
- Ventral gills
- rays 1 m - over 6 m long
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Chondrichthyes Facts
- First fossils form the Early Devonian (416mya)
- Key Characteristic - no bone in the endoskeleton
- - Derived character (not ancestral to vertebrates)
- Modern Looking sharks by the Jurassic (200 mya)
- - Snout (overhangs mouth)
- - Solid calcified vertebrae
- - Thicker, more complex teeth
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tooth Whorl
- All living and extinct sharks
- Tooth replacement every week
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Sharks
- Huge diversity in size (25cm to 12m or more)
- Nearly all are top carnivores in their food chain
- - Apex predator
- Whale shark and basking shark are filter feeders
- Chemoreception down to 1 part per 10 billion
- Excellent low - light vision
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Shark Reproduction
- Internal fertilization
- Oviparity - egg hatches outside the moter
- - 6 - 10 months to hatch
- Viviparity - egg hatches within the mother
- - Embryos feed on siblings/eggs
- - Oviducts secrete milky substances in mouth and gills
- - Yolk sac placenta
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Shark Conservation Issues
- Long lifespan, relatively few offspring
- Disruption of habitat - young prey to larger sharks
- Fishing
- - Shark Fin Soup ban in Caolifornia this week ( US 1 bowl = $100)
- - Mako Shark Steaks
- - Fish and Chips
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Skates and Rays
- Dorsal - ventral flattening
- enlarged pectoral fins
- appear to be derived from extinct early sharks
- skates - oviparous, rays - viviparous
- eat primarily small invertebrates and fishes
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Ratfishes
- Holocephali
- Not well known
- Deep water
- Feeds on invertebrates
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Life in Water
- Vertebrates evolved in water (currently 73% of Earth)
- More than 50% of living species never left
- Most water is saltwater
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Habitat variety
From simple (open ocean = pelagic zone) to complex (coral reefs)
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Challenges to life in Water
- Need to adjust buoyance, push through water
- - fluid resistance, gravity not an issue
- -streamlined shapes but can get very large
- Need to maintain stable interior environment
- - ions cross freely between body and water
- Low O conent in water vs air
- Loss of body heat into water
- Water is also stable in temperature
- - good usually, difficult to escape if too hot or cold
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Gills
- Structures to exchange CO2 and O
- In teleosts (derived ray-finned fish), gills are enclosed in opercular cavities
- - covered by operculae (singular operculum)
- - valves to keep water flowing correctly (in mouth, out gills)
- buccal pumping - using mouth and operculae to pump water across gills
- ram ventilation - no pumping, swim with mouth open
- -example - some sharks, tuna, mackerel
- two columns of gill filaments per gill arch
- secondary lamellae - filaments where gas exchange takes place on the gill (microscopic, feathery)
- Countercurrent exchange - blood flows through the lamallae opposite in direction to water flow (maximizes O)
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Oxygen from Air
- some fish live in O-poor environments
- storage for gulped air, structures include labyrinth in back of head (example bettas)
- Lungs - may have evolved in freshwater placoderms
- - develop from pharyngeal region of digestive tract
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Buoyancy
- can use lungs as swim bladders (bichirs and teleosts
- swim bladder located ventral to vertebral column
- gas must be removed or added to the swim bladder as the fish swims up or down
- - either through the gut (primitive)
- - or though the blood (derived)
- - rete mirabile
- Chondritchthyes have no swim bladder
- Use liver instead
- Shark livers very dense in oil (may be 25% of body mass)
- Nitrogen compounds in the blood less dense than water
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Senses
- Vision - well developed eyes
- Taste/Smell - taste bud organs in mouth, around head, anterior find
- Olfactory organs on snout
- salmon use smell to return to home stream
- Touch - Internal ear sensitive to motion, gravity, sound, pressure
- Neuromast Cells - clusters of hair or related cells on head and body
- Lateral line system - neuromasts located on head and along body
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Lateral Line System
- Senses movement and vibration in water
- only in fish, amphibian larvae and aquatic amphibians
- Two configurations of neuromasts -
- - within tubular canals inset in the skin
- - exposed in depressions in the epidermis
- Hairs are set in the cupula
- - gelantinous material in cupula - displacement bends hairs, triggers nerves
- - provides information from all directions and along body
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Electricity
- Electrical discharge from modified muscle cells (electrocytes)
- some in defense/hunting, weakly electric in courtship
- Electroreception
- - especially know in sharks and rays
- - can detect electric fields (modification of lateral line)
- - detect prey ( can find hidden fish that can't be smelled or seen)
- - Possible also for navigaion
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Solute
- molecular dissolved in water or blood
- primarilty saly ions, urea, small carbohydrates
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Osmosis
water flows from a dilute solution to a more concentrated one
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Hyposmolal
body has lower solute concentration than surrouding water
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Hyperosmolal
body has higher solute concentration than surrounding water
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Stenohaline
narrow tolerance of salt - either fresh or salt water
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Euryhaline
wide tolerance of salt - tolerate both
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Osteichthyes
- Begin in Late Silurain ( ~ 420 mya), many by mid Devonian ( ~ 400 mya)
- - Devonian is known as the "Age of Fishes"
- Two major groups of Osteichthyes can be seen in Devonian fossils
- - anatomy of the fin ray
- Unique to Osteichthyes is endochondral bone
- - retain dermal bone
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Sarcopterygian
- Fin rays extend from central bone
- Class Sarcopterygii
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Actinopterygian
- fin ray extends from base
- Class Actinopterygii
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Class Sarcopterygii
- lobe finned fish and derived tetrapods
- - fishes - lungfishes, coelacanth
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Class Actinopterygii
- Ray finned fish - most fishes are included here
- Subclass Condrostei
- - Bichirs, sturgeon, paddlefish
- Subclass Neopterygii
- Infraclass Holostei
- - only 8 species, 7 gar and 1 bowfin (Amia Calva)
- Infraclass Teleostei
- - Everything else
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Lungfish
- extant are freshwater
- up to 1.5m long
- African and S. American - Lungs
- Australian - gills usually
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Coelacanth
- Fossils unknow after Cretaceous
- Thought to be extinct until 1938
- Deep, off shore in the Indian Ocean
- Also Indonesia
- Fat-filled swim bladder with ossifised walls
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Actinopterygii
- Ray-Finned fish
- Subclass - Condrostei
- Skeleton mostly cartilage (except Bichir)
- Bichir - Africa
- Sturgeon - Norther Hemisphere
- Paddlefish - Mississippi River Valley and Yangtze River Valley (China
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Actinopterygii
Subclass - Neopterygii
- Infraclass - Holostei
- Primitive fishes (only 8 species)
- Temperate fresh and brackish water
- gar - thick scales, few predators (alligator
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Infraclass Teleostei
- Class Actinopterygii
- Subclass Neopterygii
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Cichlids Family
- Cichlidae
- Diverse group of teleosts
- all have pharyngeal bones fused into one bone with teeth
- - pharyngeal jaws (evolved from gill arch)
- species number between 1,300 - 3,000
- popular in aquaria but also model species for evolution
- parental care, including mouthbrooding
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Lake Malawi Cichlids
- Very large and deep freshwater lake in the Great Rift Valley (east Africa)
- Over 700 Species of cichlid = evolutionary radiation
- Formed by plate tectonics - less than 2 million years old
- cichlids live in every habitat (open water, lakebed, deep water etc)
- some have color change and mimicry; sex change
- model for how new species evolve
- diversity of feeding forms - jaw/mouth morphology
- - trophic specialization
- occupy every part of the food web
- feed on plankton, arthropods, algae, ectoparasites, fish eggs, fish
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Ventral
to the front/belly
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Proximal
Near to the trunk
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Distal
Distant from the trunk
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The Paleozoic Era
- 542 - 251 mya
- Era in which vertebrates arose and diversified
- by 251 mya, first mammals, dinosaurs, crocodiles, and teleosts all evolved
- Major Continental drift
- - land mass contact changes
- - Latitude shifts
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Continental Drift
- Hypothesis inspired by the shape of South America and Africa
- Formalized by Alfred Wegener
- Supported by the theory of plate tectonics in the 1950's and 60's
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Mid Paleozoic
Ample warm, shallow sea floor
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Late Paleozoic
- Pangaea (one large continent)
- Continental collisions
- - formed the appalachians
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Pangaea
- Huge, arid inlands with temperature extremes
- (continental climate)
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Late Cambrian
- 514 mya
- Some modern tropical areas are polar (S. America)
- Canada is in the Tropics
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Paleozoic Ecology
- Terrestrial plants were ferns early
- by end of period, lots of conifers
- Large terrestrial vertebrates by end of Paleozoic
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Carboniferous Period
- 359 mya
- Huge forests created lots of atmospheric oxygen
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Permian/Triassic Extinction
- Larges extinction event in history
- 251 mya
- 95% of all marine life
- 12 families of fish
- 27 tetrapod families (49%)
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Causes of the Permain/Triassic extinction
- Know to have lower oxygen concentration in water, higher CO2 (more acid)
- - Many species evolved in O - rich environment
- Massive volcanic eruptions in Siberia
- - Siberian Traps
- - USA- sized area covered in Lava
- Volcanic Eruptions - trigger global warming
- - Dust clouds block sun - lower photosynthesis
- -- initially colder than normal
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Climate change caused by Permain/Triassic Extinction
- Volcanic Eruptions - Trigger global warming
- CO2 and sulfur into the air, acid rain
- Greenhouse effect begins
- higher temperatures melt underwater frozen methane - feedback loop
- Temperature increased about 6 degrees C
- ---Took about 30 million years for life to recover diversity
- Waters warmed at higher latitudes - distuption of ocean circulation
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Major Tetrapod survivor of the Perimain Extinction
- Lystrosaurus
- pig size
- 2 canine teeth (dicynodont)
- Therapsid = mammal-like reptile
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