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Vertebrate Movement to Land
SZ2- Students will explain
evolutionary history of animals
over the history of life on
earth.
• Tetrapods- Animals with 4
limbs
– Amphibians
– Reptiles
– Birds
– Mammals
• Evolved from fish
1
Transition from Sea to Land
2
•Coelacanth
3
Eusthenopteron
4
Panderichthys
5
Tiktaalik
6
7
Transitional Tetrapods
Skull, teeth, limbs similar to lobefinned fish
Acanthostega
Ichthyostega
9
Amphibians
11
Adaptations to live on land
•
•
•
•
Gills are usually lost
Lungs function
Breathe through skin
Secrete mucus
– Prevent dehydration
– Aids in respiration
12
More Adaptations to live on land
• Skeleton
– Fins evolve into limbs
– Vertebral column
supports body
underneath it
AIR IS NOT AS BOUYANT AS
WATER.
13
Evolution of Circulation
Fish
Amphibian
14
Kingdom Animalia
Phylum Chordata
Subphylum Vertebrata
Class Amphibia
1st land vertebrates
Ex: frogs, toads, & salamanders
Class Amphibia – “Double Life”
frogs, toads, salamanders, & newts
Characteristics
• “Double Life” -lives part of
its life in water and part
on land
• Ectothermic- “outside
heat”- body temp.
regulated by environment
• no scales or claws
• Have thin, moist skin
AMPHIBIAN METAMORPHOSIS
•
•
•
•
Egg- tadpole- adult
larvae are herbivores, adults carnivores
larva have tails to move in water
external fertilization with no parental care
lay eggs without shells in water
18
19
• Amphibian Body Plan
– Bilateral symmetry
– 3 chambered heart
– Larvae breathe through gills; adults breathe
through lungs
– Breathe through thin, moist skin (produces
mucus)
– Changes from larva to adult through
the process of metamorphosis
Class Amphibia
Order Anura
•
•
•
•
Anura- an=without, ura= tail
Tailless
Hindlegs adapted for jumping and swimming
Tympanum (ear drum) and larynx well
developed
Ex. Frogs and toads
frog dissection introhttp://www.kizoyunlari.com/files/file/kurbaga_ameliyat.swf
Class Amphibia
Order Caudata
• Caudata- “have a tail”
• Long tail
• 2 pairs of limbs
Ex. Salamanders and newts
Class Amphibia:
Order
Gymnophiona(Apoda)
Gymnos- naked
ophis- snake
live in tropics
Elongated body
Limbless
carnivores
Ex. Caecilians – “blind”-small eyes
Kingdom Animalia
Phylum Chordata
Class Reptilia
Ex: snake, turtle, lizards
crocodile, dinosaurs
Reptilian Traits:
3 chambered heart (except for crocodilians- imperfect 4)
Ectothermic
Paired limbs with five toes and claws
Tough, dry, scaly skin (horny epidermal scales)
Jaws adapted for crushing and gripping
Breathe with lungs
metanephric kidney- produces uric acid to reduce water loss
Large cerebrum as compared to rest if brainbehaviors- 1. instinct
2. learned
Reptile Legs
• Short tetrapods for
walking
• Positioning of the legs
more directly under
the animal. This
position provided more
support than the
splayed arrangement
of the Amphibian legs.
Reproduction:
Internal fertilization (to avoid desiccation of
gametes), oviparous
Lay amniotic eggs on land- no dependence on water
Shells leathery, sometimes calcareous
Amniotic Egg Structures & Functions
• Chorion provides a special hard covering that is permeable to
respiratory gases (O2 and CO2) while being impermeable to water
vapor.
• Allantois is a storage reservoir for metabolic waste products such
as nitrogenous compounds and gas exchange.
• Amnion is a fluid filled sac that acts as a cushion for the embryo
and also prevents desiccation.
• Yolk sac contains food for the embryo, thus eliminating the need
for a larval stage.
Phylum Chordata
Subphylum Vertebrata
Class Reptilia
Order Testudine:
Body in a bony case
-dorsal carapace(top of shell)
- ventral plastron(bottom of shell)
Jaws with a horny beak, no teeth
Vertebrae and ribs fused
Ex. Turtles and tortoises
Turtle Shell Anatomy
Fusion of ribs, vertebrae, & carapace
Turtle Life Cycle
Phylum Chordata
Subphylum Vertebrata
Class Reptilia
Order Sphenodonta
• Primitive reptile
• closely related to dinosaur
• Looks like lizard
• Diapsid skull
Ex. Tuatara- only living species
Phylum Chordata
Subphylum Vertebrata
Class Reptilia
Order Squamata
Diapsid skull with two temporal openings
Skin is shed with horny epidermal scales
Jacobson’s organ- sense of smell
Movable skin, kinetic skull
Poisonous- hemotoxins (blood) , neurotoxins(nervous system)
EX. Snakes and lizards
Lizards have movable eyelids
Snakes- descended from tetrapod ancestor
Phylum Chordata
Subphylum Vertebrata
Class Reptilia
Order Crocodilia
• Elongated massive skull
• Imperfect 4 chambered heart
• crocodiles, alligators, and caimans, gavials
Crocodilians
Crocodiles, Alligators,
Caimans, & Gavials
Gavial(gharial)
Carnivores, “ghara”- pot- bulb on
snout
12.25- 15.5 ft. long
Rivers of India, Nepal, Pakistan,
Bhutan, Bangladesh
Critically Endangered
Alligator
Crocodile
Largest, best predatos
Live in/near Salt water
American Crocodile- Endangered
Most in Australia
Caiman
Rivers/swamps of Central and
South America
3ft- 16 ft. (only in black caiman
species)
Crocodilian Reproduction
• The temperature inside the nest of several crocodilian
species decides the sex of the young. ~50-80 eggs
• If the nest temperature is 30ºC, females will hatch
• If the temperature is above 34ºC - males.
• If the temperature is in between- young of both sexes.
Land Adaptations for Reptiles
•
•
•
•
•
•
•
Legs underneath bodies (tetrapods)
Lungs
more efficient circulatory system
Scales- prevents dehydration, protection
Claws
Amniotic egg
The excretory waste of the reptiles is uric acid
unlike the dilute, water wasting ammonia in
the urine of Amphibians