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Chordata: Amphibians, Reptiles and Birds

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1 Chordata: Amphibians, Reptiles and Birds
By: Nikita Mathew, Noor Al-Alusi, Sara Shu Period 3

2 Amniotes An amniote is a member of a clade of tetrapods that have an amniotic egg containing specialized membranes that protect the embryo (i.e. mammals, birds and other reptiles). Embryonic membranes distinguish amniotes from tetrapod amphibians.

3 AMPHIBIANS

4 Phylum: Chordata Class: Amphibia Salamanders
-Order: Urodela “tailed ones” Frogs -Order: Anura “tail-less ones” Caecilians -Order: Apoda “legless ones”

5 Sample Animals

6 Body Cavity Body Symmetry Has Coelom Bilateral symmetry

7 Nervous System Present Brain has medulla, cerebellum, a small cerebrum
Has spinal cord and nerves Two eyes with third eyelid/protective membrane

8 Circulatory System Are cold blooded (body temperature same as surrounding environment) Three chambered-heart with two atria and one ventricle

9 Digestive System All amphibians use mouth, stomach, and small intestine for digestion Frogs have a long sticky tongue that is usually folded backwards in their mouth

10 Excretory System Two kidneys are the main excretory organs
Filter waste that leaves the body as urine Liquid and solid wastes leave through cloaca

11 Locomotion/Musculature
Frogs and salamanders are tetrapods (“four feet”) Most frogs and salamanders use strong hind legs to move Caecilians burrow in moist soil because they are legless

12 Skeletal Type Endoskeleton—consists of hard supporting elements (cartilage and/or bone) Has axial skeleton (skull, backbone, and ribcage) and appendicular skeleton (limbs) Skeleton provides support and enables movement

13 Sensory Structures/Features
Frogs and salamanders have eyes while caecilians are nearly blind Can sense vibrations on the ground Frogs have external eardrums that sit behind the eyes

14 Reproduction: Frogs and Salamanders
Sexual reproduction Eggs laid and fertilized outside of mother’s body in water/moist environment Eggs lack shell so are prone to dehydration so amphibians lay them in moist environments with a jelly-like layer for protection

15 Reproduction: Caecilians
Only amphibians to use internal insemination Fertilized eggs are laid outside and guarded by female When hatched, caecilians are already metamorphed

16 Gas Exchange Mostly rely on moist skin for gas exchange
Breathe using positive pressure Lowers roof of mouth and take in air through nostrils. Nostrils then close and roof of mouth is raised, pushing air into lungs.

17 Other features Amphibian means “two lives” (many live in aquatic and terrestrial environments) Have complex social behaviors, including certain vocal communication during breeding

18 Reptiles Phylum: Chordata

19 http://derek4messiah. wordpress

20 Body Symmetry Body Cavity present bilateral

21 Nervous System Nervous system consists of a brain, spinal cord, and sense organs. More advanced nervous system than amphibians Reptiles have much smaller brains compared with mammals Olfactory bulb Snake’s tongue have highly sensitive smell sensors. Alligators have sensory nodules on jaws, connect to nerve fibers responding to vibrations and small pressure changes in the water. Crocodiles have similar organs on almost every scale on their body

22 Circulatory System Cold blooded- do not use metabolism to control body temperature Behavioral adaptations to regulate body temperature Ectothermic-absorption of external heat as main source of body heat

23 Digestive System Present [mouth, teeth, esophagus, stomach, rectum]
Snakes: loosed articulated jaws and elastic skin to swallow prey larger than itself

24 Excretory System Cold blooded Covered with scales
Kidneys and ureters to get rid of liquid wastes Molt/shed their skin

25 Locomotion/Musculature
Snakes use waves of lateral bending to propel themselves forward They also grip ground with belly scales at several points, pulling its other parts forward. Other Reptiles: -stomachs close to ground - low center of gravity forces body to work more

26 Skeletal Type endoskeleton Breast bone protects lungs and heart
Turtles have a hard shell that are fused to the vertebrae and ribs; defense against predators.

27 Sensory Structures/Features
Scales that contain keratin—provides waterproof barrier that helps prevent dehydration in dry air Snakes: -acute chemical sensors and lack eardrums— their sensitivity to ground vibrations help them detect movement -flicking tongue helps to fan odors toward olfactory organs on roof of mouth

28 Reproduction Sexual Female’s eggs fertilized internally
Eggs, with a leathery and flexible shell, are then deposited

29 The Amniotic Egg extraembryonic membranes protect the embryo.
gas exchange, waste storage, transfer of stored nutrients to embryo Amnion: a fluid filled cavity that cushions against shock Is not found in amphibians

30 Gas Exchange Watertight skin (due to scales) not used as respiratory surface. Most rely solely on lungs for gas exchange Turtles also use moist surfaces of cloaca.

31 Unique Features Some lizards can lift their front legs off the ground while running

32 Birds Phylum: Chordata

33 Sample Animals Ostrich Finch Ducks Toucan
Ducks Toucan

34 Body Cavity Body Symmetry Present (has coelom) Bilateral symmetry

35 Nervous System Present
The central nervous system is composed of a brain, a spinal chord, and nerves. The autonomic nervous system controls heartbeat, breathing, and digestion.

36 Circulatory System Present Warm-blooded
Heart pumps blood through body to give energy to all parts of the bird Birds have a four-chambered heart to keep tissues well supplied with oxygen and nutrients, supporting a high rate of metabolism.

37 Digestive System Present
Beaks evolutionarily modified according to diet/environment The crop organ is unique to birds, stores food, continuously supplies small amounts of food to the stomach Stomach has two parts: Proventriculus (secretes digestive juices) & Gizzard (gravel and muscles grind up food) Extremely high metabolism

38 Excretory System Two kidneys are the main excretory organs
Birds lack a urinary bladder Both liquid and solid wastes are excreted through cloaca

39 Locomotion/Musculature
Wings (made of B-keratin) adapted for flight Power for flapping comes from contractions of the large pectoral attached to sternal keel Some birds have wings adapted to soar on air currents and flap their wings only occasionally Ratites = flightless birds (lack sternal keel and enlarged pectoral muscles)

40 Skeletal Type Internal skeleton Two legs and two wings
Reduction in weight facilitates flight (no teeth, no jaw bones, reduced skull) Hollow bones make bones stronger, not lighter Sternal keel allows for flight (not present in ratites)

41 Sensory Structures/Features
Well developed mid brain -> acute vision Excellent sense of hearing Reduced olfactory lobes -> poor sense of smell Large Corpora Striata -> instinctive behavior (i.e. feeding, flying, reproduction, etc.)

42 Reproduction Sexual reproduction Eggs fertilized internally
Eggs have protective shell

43 Reproduction (cont’d.)
Birds engage in elaborate courtship rituals during breeding season

44 Gas Exchange Complex respiratory system
Air goes into nostrils -> trachea -> syrinx -> bronchi -> lungs -> abdominal air sacs ->lungs -> other air sacs -> up the bronchi

45 Other Unique Features Wide range of feet and beaks, adapted to the environment and food A bird’s brain is actually 10x larger than a non-bird reptile’s, and only slightly smaller than a mammal’s

46 QUIZ! Of the amphibians (frogs, salamanders, caecilians), which organisms use external fertilization? Frogs Salamanders Caecilians Both A and B

47 ANSWER: D (eggs of frogs and salamanders are fertilized outside the body while caecilians’ eggs are fertilized internally)

48 2. Platyhelminthes, birds, amphibians, and reptiles all possess:
a. A true circulatory system b. A true respiratory system c. Bilateral Symmetry d. Coelom e. A vertebrae

49 ANSWER: C (amphibians, birds, reptiles, and Platyhelminthes all have bilateral symmetry)

50 3. Which of the following are cold-blooded? 
A. Amphibians B. Birds C. Reptiles D. Both A and C

51 (amphibians and reptiles are cold blooded)
ANSWER: D (amphibians and reptiles are cold blooded)

52 4. True or false: Amphibians use amniotic eggs in their reproductive process
   

53 (reptiles and birds use amniotic eggs)
ANSWER: False (reptiles and birds use amniotic eggs)


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