Vertebrates: Fish to Reptiles Ch. 34
Phylum: Chordata
Characteristics common of all chordates
• __________________________ – later modified into the brain and spinal cord
– Other animal phyla = ventral nerve cord
• ___________– a flexible, internal, support structure (in most vertebrates by
cartilage or bone early in development)
• _______________– used in respiration (only present in embryos of land
chordates)
• __________________________– disappears in some (e.g. humans)
3 subphyla of the chordates:
Subphylum: __________________
• 3 classes of animals
• Biggest are marine tunicates (sea squirts)
• Lack ___________________ and notochord as adults but have all chordate
characteristics as larvae
Subphylum __________________ (Lancelets)
• Small marine animals
• Most common is amphioxus – small eel-like creature
Subphylum __________________– key feature is a flexible spinal column made of
vertebrae extending from anterior to posterior
Characteristics:
• __________________ (individual segment of backbone)
• __________________symmetry
• Dorsal, hollow nerve cord (anterior = brain)
• __________________skeleton
• 2 pairs of jointed appendages
• Organ systems (e.g. heart – 2 to 4 chambers and closed circulatory system and
respiratory – lungs or gills)
– coelom contains digestive, excretory, and reproductive organs
• Body covering: skin often 2layers and forms scales, feathers, glands
• __________________ (“cold-blooded) or __________________ (warm-blooded)
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5 main classes of vertebrates
Ectothermic (body temp changes with environment)
• __________________– Jawless Fish, Cartilaginous Fish, Bony Fish
• __________________– Salamanders, Frogs and Toads
• __________________– Crocodiles and Alligators, Turtles, Lizards and Snakes
Endothermic (constant body temp independent of environment)
• __________________
• __________________
Question1: What characteristics distinguish chordates from other animals?
Answer1:
Question2: What basic characteristics distinguishes vertebrates from the other chordates?
Answer2:
Fish – 4 classes
Class __________________– (E.g. Lamprey)
• Snake-like bodies, no paired fins, true jaws, or
scales
• Most are __________________– using sucker-like
mouth and teeth to “chew” a hole in host and suck
blood/body fluids
• Cartilaginous skeleton
Class: __________________– Hagfish
• Marine animals feeding on worms and dead
animals
• a.k.a. “slime eels” because they use slime as a
defense mechanism
• Use ‘__________________instead of a jaw to
eat
Cartilaginous Fish – evolution of movable jaws
Class: __________________
• Sharks, rays, skates
• Moveable upper and lower jaws
• Skeleton is entirely __________________
• 2-chambered hearts
• No __________________or muscled operculum
(gill cover) therefore they must swim
continuously so they don’t sink and can breath
• Skates and Rays – flattened bodies feeding on mollusks and crustaceans
• Stingrays – poisonous stingers in tail
• Electric rays - produce electric charge to stun prey
• Rays – young are born live (__________________)
• Skates – egg laying (__________________)
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Sharks – most are meat eaters and active
hunters
Very tough scales
Main hunting senses:
• olfactory sacs – to smell prey
• __________________– detect vibration
of prey
Bony fish
Class: __________________
• __________________and overlapping scales for protection
• Jaws are present with many teeth in mouth
• Most of the body is muscle
• Most have a swim bladder – help float by increasing/decreasing amount of gas
• Respiration by gills supported by bony gill arches and covered by an operculum
• Circulation consists of __________________heart, arterial and venous systems,
and four pairs of aortic arches
• Complex nervous system of brain, olfactory lobes, optic lobes, spinal cord, lateral
line…
• Sexes are separate- usually __________________fertilization
• Bony fish vary greatly in size and shape
Question1: List the general characteristics of bony fish.
Answer1:
Question2: What structures aid in maintaining balance and controlling the direction of
movement in bony fish?
Answer2:
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Class ____________________ – frogs, toads, salamanders, newts
• Shows vertebrate evolution: ____________________
• First land vertebrates for 75 million years before reptiles
• Parts of life are on both land and water
– Fully aquatic embryos and larvae
– Most need water for ____________________ – sperm released into the
water to fertilize the eggs - external fertilization
– Adults need ____________________ environments
• Thin skin with ____________________ glands
• 3 chambered heart (2 atria, 1 ventricle)
• 2 pairs of limbs on lateral edge – better for swimming
• Respiration is by ____________________ (nostrils connected to the mouth), gills,
and ____________________
We will study the frog – a good representative and anatomy resembles most vertebrates
_____– dry, rough, warty skin and can live away from water but need water to reproduce
Frog Features - External Features
• Short, broad body, 2 forelimbs and 2 muscular hind-limbs
• Eyes – ____________________ – upper, lower, and ____________________
(allows the frog to see underwater)
• ____________________ – ‘ear’
• 2 nostrils at upper tip of head – Why?
Circulatory System
• _______________________ – 2 atria and 1 muscular ventricle (CO2 and O2-rich
blood not separated)
• Closed system with ____________________
Know the flow of blood through the frog
Respiratory System
• In adults – use of ____________
• ____________ – external gills which are
then absorbed as the lungs form
– The skin (thins, moist, and with
many blood vessels) plays a small
role in respiration but is the main
organ of respiration during ____________________
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Nervous System
• Central nervous system – _____________________________
• ____________________ nervous system – nerves separate from the spinal cord
• Lobes of the brain
1. ____________________ (smell)
2. ____________________ (sight)
3. _______________(interprets sensory info and voluntary muscle action)
4. ____________________ (balance and coordinates movement)
5. ____________________ – (controls involuntary muscle action)
Excretory System
• Most ____________ is excreted by
skin
• Other wastes excreted by
____________ which filter the blood to form
urine
• Urine is carried from the ureters (tube)
to the bladder and then to the
______________ before leaving the body
– Cloaca – a common opening to
expel ____________________
Reproductive System
• ____________________ fertilization
• Mating – ____________________ – male clasps the female with forelimbs and as
eggs leave female body, the male releases sperm over the many eggs
• Tadpoles (fish-like with gills, no legs or protection from the mother)
• ____________________ – develops legs, absorbs tail and gills, and develops
lungs, 3-chambered heart
– This may take 3 months to 3 years depending on the type of frog
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Question1: An ecologist studying a local frog species observed that the population
declined in years with droughts in the spring but was not affected by droughts at other
times of the year. How would you explain this observation?
Answer1:
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Class ____________________ – lizards, crocodiles, turtles, snakes
Characteristics:
• Well suited for life on land -do not require water for reproduction
– ____________________ fertilization with thick, leathery eggs
• No ____________________
• Dry, scaly skin – protect against water loss
• 2 pairs of legs (except snakes)
• Well developed respiratory system – protected by ____________________
• Well developed excretory system producing a semisolid paste for urine –
____________________
• ____________________ – 2 atria and 1 partly divided ventricle (less mixture of
oxygenated and deoxygenated blood)
Crocodiles and Alligators - 2.5 meters to 7 meters long
Differences:
• ____________________ — Alligators tend to have wide, U-shaped, rounded
snouts, while crocodiles tend to have longer, more pointed, V-shaped snouts.
• ____________________— The fourth tooth on the lower jaw sticks up over the
upper lip on crocodiles, so you can see it when their mouths are closed. In
alligators, this fourth tooth is covered up.
• ____________________ — Crocodiles also have special glands in their tongues
that can get rid of excess salt, so they tend to live in saltwater habitats. Alligators
have these glands, too, but they don't work as well as the crocodiles', so alligators
prefer to live in freshwater habitats.
• With 23 species of crocodilians, though, these general rules don't always apply—
there are exceptions!
Turtles
• ____________________
• Turtles live primarily in the water, while tortoises are land dwellers
• Herbivore or carnivores (though they have no teeth)
• Some marine turtles can be up to 2 meters long and over 500kg
Lizards
• Well distributed
• Range from small (gecko) to very large (_________________ more than 100kg)
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Snakes
• Body – ________________________________________
• ____________________ detects odor
• May or may not be venomous
– Venomous – ____________________ – poisons attack nervous tissue
– ____________________ – break down red blood cells
• Others may be constrictors
Question1: Name two characteristics of reptiles that are important adaptations for life in
arid climates.
Answer1:
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