Unit #4: Organizing Biodiversity
Domain Eukarya (3)
“The Phyla of
Kingdom Animalia”
“The Sponges”
Digestion
Intracellular by Diffusion
Gas Exchange
Diffusion
Excretion
Diffusion
Transport
Diffusion
Nervous System
Reproduction
Basic Nerve Nets and Isolated
Nerve Cells
Asexual – Gemmules or budding
Sexual – amoebocytes modified
as sperm or egg
Body Cavity
Acoelomate
Symmetry
Mostly Asymmetric
(some radial)
Sponges were once thought to be plants but are now
believed to be a separate evolutionary line of
animals.
The body of a sponge forms a wall around a central
cavity. In this wall are thousands of tiny openings or
pores. A steady current of water pushed by the
flagella of collar cells moves through these pores into
the central cavity. This current of water exits
through a large hole called the osculum at the top.
The water delivers food and oxygen to the cells and
carries away waste products.
Many sponges manufacture thin, spiny spicules that
form the skeleton of the sponge. A special cell called
an amoebocyte builds the spicules from chalk-like
calcium carbonate or glass-like silica. The softer
sponges we use as natural bath sponges consist of
fibers of a protein called spongin.
Sponge asexual reproduction occurs through the
production of Gemmules. These are sphere shaped
amoebocytes surrounded by a protective layer of
spicules. Gemmules can survive long periods of
freezing or drought, and will grow into new sponges
when conditions return to favorable. Asexual
reproduction through budding occurs when part of
the parent sponge falls off and becomes a new one.
Sexual reproduction occurs through the release of
large amounts of sperm into the water, with hopes
that the sperm will reach the egg cells kept in the
body wall of other sponge plants.
Sponges provide habitat for other organisms and
have symbiotic relationships with other sea
creatures. They are the fungus of the sea as they
clean up the ocean floor. We use their skeletons for
bathing and the chemicals they produce for
protection have been found useful in treating
bacterial infections (like penicillin resistant strep
throat), leukemia, herpes virus, and arthritis.
Digestion
Mostly extracellular
(Gastrovascular cavity)
Gas Exchange
Diffusion
Excretion
Diffusion
Transport
Diffusion
Nervous System
Nerve nets
Reproduction
Asexual –budding
Sexual – testis, ovary,
hermaphrodites, external fertilization
Body Cavity
Acoelomate
Symmetry
Asymmetric/ radial
Cnidarians
Cnidarians are soft-bodies animals with stinging
tentacles in a circle around their mouth. They exist
as individuals or in colonies.
Life cycle:
Cnidarians capture and eat small animals using
stinging tentacles called nematocysts (located on the
tentacles). These cells are poison filled sacs with a
spring-loaded dart.
They have sensory cells for detection. Statocysts are
cells that detect which way is “up” and ocelli are eyespots that detect light.
Class Hydrozoa – the Hydras
Hydras spend most of their life as a polyp, as the
medusa stage is short-lived.
Class – Scyphozoa – the Jellyfish
Jellyfish spend most of their time as a medusa. In
the north Atlantic ocean have been known to be as
large as 2m in diameter. The largest ever recorded
was 3.6m in diameter with tentacles 30m long! Most
jellyfish stings are not deadly except for the
Australian jellyfish – toxin kills in 3 to 20 min.
Class Anthozoa – Sea anemones and coral
Only polyps, no medusa stage. These often have
photosynthetic symbionts. Coral are like anemones
but have a skeleton of calcium carbonate.
Cnidarian symbiotic relationships provide food and
shelter to other animals (remember Finding Nemo?).
Coral reefs protect shore lines and provide food and
shelter for other organisms.
“The Flatworms”
Digestion
extracellular
(mouth, intestine, no anus
Incomplete/sac system)
Gas Exchange
Diffusion
Excretion
Tubule network and flame cells
Transport
Diffusion
Some centralization and
cephalization
Nervous System
Brain, eyespots,
2 ventral nerve cords
Asexual –fission and regeneration
Reproduction
Sexual – hermaphrodite
Body Cavity
Acoelomate
Symmetry
Bilateral
Flatworms
Flatworms are the simplest animal with bilateral
symmetry. They have the beginnings of organ
development and an anterior (front) and posterior
(rear) end.
Free-living flatworms are scavengers. Because they
have a mouth and no anus, any undigested food is
expelled through the mouth. Parasitic flatworms, like
tapeworms, do not always have digestive tracts.
The flatworms do not have a circulatory system, as
they are so flat they can depend on diffusion.
However, they have special cells called flame cells to
expel excess water.
The flatworm nervous system shows cephalization,
as there is a simple brain. Centralization is seen by
the two nerve cords, and specialization by the ocelli
(eye-spots that detect light) and chemical sensitive
cells.
Flatworms move using cilia and muscles to twist and
turn.
Reproduction is both asexual and sexual. Asexual
reproduction is accomplished through fission; the
worm breaks into pieces, and each piece becomes a
new worm. Most free-living worms are
hermaphrodites, having both male and female sex
organs.
Class Turbellaria – Planarians
These free-living worms are the “cross-eyed”
flatworms. Most are less than 1cm in length.
Regeneration in Planaria:
Cutting between the eyespots of
a Planaria results in a split into
two identical organisms by
regeneration.
Class Trematoda – Flukes
Flukes are internal or external parasites. Most are
less than 1cm long, and their life cycles usually
involves multiple hosts.
Most flukes are hermaphrodites and undergo sexual
reproduction to produce more eggs than free-living
flatworms – 10,000 to 100,000 times more.
Ex: Blood Fluke
Blood flukes live in the tiny blood vessels of human
intestines. They lay so many eggs that the tiny
vessels of the host break open and leak eggs and
blood into the intestines. The eggs are then excreted
in the feces. This way they may enter the water
system (mostly in undeveloped countries). The egg
hatches into swimming larvae that burrow into a
certain species of snail. The worms reproduce
asexually inside the snail. These new worms break
out of the snail. If they find a human, the worms
bore through the skin and eat their way into the
blood vessels to be carried to the intestines to start
the cycle over.
Class Cestoda – Tapeworms
Tapeworms are long, flat parasitic worms that have a
head called a scolex with several suckers and a ring
of hooks. These structures attach to the intestinal
wall and absorb food through their body wall. Adult
tapeworms can be up to 18m long. Tapeworms
almost never kill their host.
The body of the tapeworm is made of sections called
proglottids which contain little more than male and
female reproductive organs. The eggs can be
fertilized by sperm from other worms or the same
worm. Fertilized tapeworm eggs are released when
the mature proglottid breaks off and bursts open to
release over 100,000 eggs.
If food or water contaminated with tapeworm eggs is
consumed they hatch into larvae and burrow into
muscle tissue to form a cyst. If humans eat raw or
undercooked meat with these cysts the worm
become active in the intestines of the human.
“the Roundworms”
Digestion
extracellular
(mouth, intestine, anus
“tube in tube system”)
Gas Exchange
Diffusion
Excretion
Long, string-like tubules
Transport
Diffusion
Nervous System
String-like nerve cord
Some centralization
Reproduction
Sexual – separate sexes
Body Cavity
Pseudocoelomate
Symmetry
Bilateral
Roundworms are the simplest animals with a “tube
with-in a tube” digestive system; mouth and anus.
Roundworms range from microscopic to a meter in
length. They are found all around us – a rotting
apple may contain as many as 90,000 roundworms.
Roundworms have bilateral symmetry and may be
free-living or parasitic.
Roundworms show cephalization as they have
several ganglia in the head region and specialization
with chemical sensitive cells.
Roundworms move by contracting the muscles that
run length wise down their body. Their reproduction
is sexual, and fertilization is internal in the female.
The lifecycles are complicated and often involve
multiple hosts.
Ex: Ascaris
A parasitic roundworm that lives in humans. Adult
Ascaris live in the intestines of humans where they
produce eggs that are passed out in the feces. If
food or water contaminated with feces is ingested
the eggs hatch in the intestine if the new host and
enter the surrounding blood vessels. They are
carried in the blood and end up in the lungs where
they break out into air passages. The worms climb
up into the throat where they are swallowed and
carried back into the intestines.
Ex: Hookworms
As many as ¼ of people in the world are infected
with hookworms. The eggs hatch and develop in the
soil. If they find an unprotected foot they burrow into
the skin and enter the bloodstream. They travel to
the lungs, down the throat and into the intestines
where they dif into the intestinal wall and suck the
blood of the host.
Ex: Trichinosis
Caused by the roundworm Trichinella. Adult worms
live and bred in the intestines. Females carrying
fertilized eggs burrow into the intestinal wall and
release up to 1500 larvae which travel through the
bloodstream and burrow into the organs in the body
causing terrible pain.
The worms burrow into the muscle and form cysts.
To complete their lifecycle the infected muscle must
be eaten. Humans are infected by eating
undercooked pork.
Ex: Eye worms
They are found in Africa and affect humans and
baboons. They burrow through the tissues just below
the surface of the skin. In their travels they
occasionally move across the surface of the eye –
hence the name eye worm.
“the Segmented Worms”
Digestion
extracellular
“tube in tube system” with
accessory organs
(mouth, crop, gizzard, intestine, anus)
Gas Exchange
Diffusion through skin
Excretion
Nephridia
Transport
Closed circulatory system
Nervous System
Cephalization and Specialization
Brain and ventral nerve cord
Reproduction
Sexual – hermaphrodite
Body Cavity
Coelomate
Segmented
Symmetry
Bilateral
Annelids or segmented worms range from less than
½mm to 3m long. They have bilateral symmetry and
long tubular bodies segmented by septa.
The digestive system has a mouth and anus, as well
as a pharynx which can extend out or the mouth to
catch prey, stick to food or suck up particles.
Aquatic annelids have gills and terrestrial annelids
respire by diffusion through their skin. Since
respiration needs a moist surface, annelids secrete a
protective covering called a cuticle.
Segmented worms have a closed circulatory system
with 2 vessels that run the length of the body with
rings in each segment connecting the dorsal and
ventral tube.
Annelids excrete nitrogen wastes through tubules
leading out the body of the worm called nephridia.
Centralization of the nervous system is seen by the
ventral nerve cord, cephalization by the brain at the
anterior end and specialization by the photo and
chemical receptor cells and sensory tentacles in
some of the worms.
The worms can move by contracting muscles that
run lengthwise and in circles around the body of the
worm.
Annelids reproduce mainly by sexual reproduction.
Some worms have separate sexes while others are
hermaphrodites. The fertilization is external: sperm
are stored until eggs mature, then the clitellum
secretes a mucus ring around the worm into which
the sperm and eggs are released. The ring slips off
the worm and provides a cocoon for the eggs.
Class Polychaeta – Marine worms
Polychaetes are characterized by paired paddlelike
appendages tipped with bristles on their body
segments. Polychaetes live in cracks in coral reefs,
sand, mud, piles of rock, or open water.
Class Oligochaeta – The Earthworms
Oligochaetes have fewer bristles than polychaetes.
The bristles are on the ventral side of the worm and
help anchor it in its burrow.
Class Hirudinea – Leeches
Most leeches are external parasites that drink the
blood of their host. Leeches penetrate the skin of
their host with a muscular proboscis that they force
into the skin of their host or slice the skin with razor
sharp jaws. Once the wound is made they continually
suck the blood by excreting a liquid that prevents
clotting.
A leach can drink up to 10 times its weight in blood.
After this feeding it will not need to feed again for a
year.
“the Soft-bodied Animals”
Digestion
extracellular
“Tube in tube system” with
accessory organs
(mouth, stomach, intestine, anus)
Gas Exchange
Gills
Excretion
Kidney
Transport
Closed circulatory system
Nervous System
Cephalization and Specialization
Brain, ventral nerve cord, eyes
Reproduction
Sexual – separate sexes
Body Cavity
Coelomate
Symmetry
Bilateral
Mollusks evolved in the sea more than 60,000 years
ago. There are over 100,000 species divided into 7
classes based on early developmental patterns.
Mollusks are defined as soft-bodied animals that
have an internal or external shell. Most have a
special kind of larvae called a trochophore that
swims in open water and feeds on tiny aquatic
plants.
Four basic parts: foot, mantle, shell, visceral mass
Foot – contains mouth and feeding structures
Mantle – delicate tissue layer that covers body
like a cloak
Shell – made of calcium carbonate by glands
Visceral mass – internal organs
Mollusks include carnivores, herbivores, filter
feeders, detritus feeders and parasites. Some have
specialized feeding structures like the radula used by
snails and slugs which is a layer of flexible skin with
hundreds of teeth that act as sandpaper to scrape
food. Some produce a poison while others have
strong jaws. Or gills, used by clams, oysters and
scallops, to strain food from water
The gills in the mantle cavity also serve for
respiration for aquatic species. Specialized mantle
cavities resembling lungs are lined with blood vessels
and kept constantly moist for terrestrial respiration
For sessile (slow moving) species blood is pumped
through a simple heart through an open circulatory
system. The blood is not always in vessels but leaves
to travel through body sinuses to come in contact
with the tissues. Ex: snails and clams
For active species the blood travels in a closed
circulatory system. Ex: octopi and squid
Nitrogen wastes are excreted through tube shaped
organs called nephridia which remove ammonia from
the blood vessels.
Mollusks have a wide range of nervous systems.
Sessile species have statocysts (balance) and ocelli
(eyespots) while predatory active species have
complex nervous system with a brain and memory
Mollusks reproduce sexually mostly through separate
sexes. External fertilization for the aquatic species
and internal fertilization for the terrestrial species
Some are hermaphrodites – ex: snails, oysters, with
internal fertilization and the ability to switch from the
role of male sex to female!
Class Grastropoda – called Gastropods (“stomach-foot”)
Includes snails, slugs, abalones, sea butterflies, sea
hares and nudibranchs. Gastropods are protected by
shells, or bad-tasting poisonous chemicals
Class Bivalva – bivalves or two-shelled mollusks
Includes clams, oysters and scallops
Most are sessile in adult stage but have free
swimming larvae. The glands in the mantle
manufactures the shell and secretes mother of pearl
to coat the inside of the shell. A foreign object, like
sand, in between the mantle and the shell gets
coated in this and forms a pearl.
Class Cephalopoda – Tentacled mollusks
Includes octopi, squid, cuttlefish, and nautiluses
Most have 8 flexible tentacles with round sucking
discs that are used to hold on to fish and other prey.
Others, ex nautilus, have many more tentacles made
sticky by mucus. A trend in Cephalopod evolution is
a decrease in the size of the shell or no shell at all.
Cephalopods protect themselves by movement via
jet propulsion, releasing ink, and the ability (in
octopi) to change color to match their surroundings.
Mollusks are an important food source, but can cause
the eater to get sick. They are used in scientific
study as they do not seem to contract cancer.
“Animals with Exoskeletons”
Digestion
extracellular
“tube in tube system” with
accessory organs
(mouth, stomach, intestine, anus)
Gas Exchange
Gills, book lungs, tracheal tubes
Excretion
Malpighian Tubules
Transport
Open circulatory system
Nervous System
Reproduction
Body Cavity
Symmetry
Cephalization and Specialization
Pair of ganglia in head, ventral
nerve cord, eyes
Sexual – separate sexes, internal
ferilization
Coelomate
Segmented
Bilateral
Four subphyla:
Trilobita – oldest subphyla. Trilobites were sea
dweller, now all extinct
Chelicerates – includes spiders, ticks, mites,
scorpions, and horseshoe crabs
Crustaceans – crabs and shrimp
Uniramians – most srthropods; centipedes,
miliipedes, all insects
Arthropods have three key features: a tough
expskeleton, a series of jointed appendages, and a
segmented body. Other characteristics are a brain
located in the dorsal part of the head, a ventral
nerve cord, and an open circulatory system powered
by a single heart.
An exoskeleton of chitin provides support and
protection. However, as the exoskeleton is rigid it
inhibits growth and can only move at the hinges
Every mode of feeding seen in arthropods –
herbivores, carnivores, parasites, filter feeders, and
detritus feeders
Arthropods have evolved three basic types of
respiratory structures: gills, book gills and book
lungs and tracheal tubes. Most have only one of
these structures but several have a combination, and
others have no specialized structures at all. Book
gills and book lungs are unique to arthropods –
several layers of soft tissue are layered like pages in
a book. An opening called the spiracle connects the
sac containing the book lungs with fresh air outside
Most terrestrial arthropods have another respiratory
device found in no other animals. From spiracles,
long branching tracheal tubes reach deep into the
animals’ tissue to supply oxygen by diffusion.
In all mollusks a well developed heart pumps blood
through an open circulatory system into spaces in
the tissue called sinuses where gas exchange occurs
by diffusion.
Solid indigestible waste leaves the body as feces via
the anus while nitrogen wastes in terrestrial
arthropods are removed by Malpighian tubules. The
tubules remove nitrogen waste from the blood and
add it to the waste excreted by the anus. In aquatic
arthropods wastes diffuse into the surrounding
water, or nitrogen wastes are excreted through a set
of glands.
Most arthropods have a well developed nervous
system: all have a brain existing of a pair of ganglia
in the head, a nerve cord that runs ventrally down
the body with extending ganglia in each body
segment. Other sense organs include statocysts,
chemical receptors (taste) and compound eyes for
sight.
Reproduction is accomplished with separate sexes
and internal fertilization. Because exoskeletons are
rigid, in order to grow arthropods must shed their
exoskeleton or molt. Some arthropods are also
capable of metamorphosis – or a dramatic change in
form, ex: caterpillars and butterflies
Insects have four stages of metamorphosis:
Egg  Larvae  Pupa  Adult
Subphylum Chelicerata - Spiders and their relatives
(Arachnids)
All chelicerates are characterized by a two part body
and mouthparts called chelicerae, and a lack of
sensory “feelers” on the head. All have a body
divided into two parts: cephalothorax and abdomen
The anterior of the cephalothorax contains the brain,
eyes, mouth and mouthparts, and esophagus. The
posterior end of the cephalothorax contains the front
of the digestive system and several pairs of walking
legs. The internal organs are in the abdomen.
Subphylum Crustacea – the Crustaceans
Primarily aquatic, all crustaceans have a hard
exoskeleton, two pairs of antennae and mouthparts
called mandibles. The main body parts are the head,
thorax, and abdomen. In crayfish the head and
thorax are fused into a cephalothorax and covered
by a tough shell called a carapace.
Three sets of appendages:
First set of antennae: “feelers” or sensory hairs
Second set of antennae: also “feelers”
Mandibles: short heavy structures for biting and
grinding food
The appendages on the thorax vary greatly, but may
be specialized for feeding, walking, paddling,
fertilization, carrying eggs, burrowing, etc.
Subphylum Uniramia –
Centipedes, millipedes and insects
Centipedes and Millipedes are characterized by a
long, worm-like body composed of many leg-bearing
segments. They lack closable spiracles and a
waterproof coating on their exoskeleton so lose
water easily. Therefore they live in moist areas.
Insects are characterized by a body divided into
three parts (head, thorax and abdomen) with three
pairs of legs attached to the thorax, one pair of
antennae and one pair of compound eyes on the
head, two pairs of wings and tracheal tubes for
respiration.
Insects have three pairs of appendages that are used
as mouth parts including a pair of mandibles. Insects
communicate using sound, visual, chemical, and
other types of signals. Chemical communication is
done by releasing a substance called pheromones.
An example of visual communication is the dance
done by bees to indicate the distance and direction
to food.
“the Spiny-skinned Animals”
Digestion
extracellular
“tube in tube system” with
accessory organs
(evertable mouth, stomach with 5 pairs of
caeca, anus)
Gas Exchange
Gills on dorsal surface
Excretion
Gills and soft tissue
Transport
Water vascular system
Nervous System
Reproduction
Nerve Nets with some
specialization
Nerve ring around mouth and
radial nerves in arms
Sexual – separate sexes
Asexual - regeneration
Body Cavity
Coelomate
Symmetry
Radial
Echinoderms are spiny skinned animals characterized
by five part radial symmetry, an internal skeleton of
calcium carbonate, a water vascular system and
suction cuplike structures called tube feet.
Echinoderms share certain characteristics with our
phylum chordate like early developmental stages and
an internal skeleton, and thus are believed to be the
most closely related to humans of all the
invertebrates.
The body plan of adults has five part radial
symmetry around the center and so have no anterior
or posterior end and no brain. Most echinoderms are
two sided: the side with the mouth is the oral side
and the side without is called the aboral side.
All echinoderms have a unique water vascular
system that opens to the outside through sieve like
structures called madreporites. This system works
like a series of hydraulic pumps that can propel
water in or out of the tube feet creating or releasing
the suction in the suction cups.
Carnivorous echinoderms like the shell fish use their
tube feet to pry open shells of mollusks, then flip
their stomach out of their mouth, excrete enzymes
and absorbs the nutrients from its dinner. Herbivores
scrape vegetation from rocks using their five part
jaw. Filter feeders use their tube feet to capture
plankton. Detritus feeders move along the ocean
floor taking in a mixture of sand and detritus then
excrete the indigestible material.
In most species the thick-walled tube feet are the
main respiratory surface, while others have small
outgrowths called skin gills. Because the functions of
respiration and excretion occur at the tube feet all
over the body, a transport system is not necessary.
Solid waste exits the body through the anus in the
form of feces, and nitrogen wastes are excreted in
the form of ammonia and diffuse away.
Echinoderms have a very primitive nervous system.
There is a nerve ring that surrounds the mouth and
radial nerves that connect the ring with the body
sections. Many species of echinoderms also have
sensory cells for chemicals and light.
Movement is accomplished through the tube feet and
a thin layer of muscle attached to the endoskeleton.
The degree of movement is determined by the
jointedness and flexibility of the endoskeleton; some
are fused while others are jointed.
Most echinoderms are male or female, but some
species are hermaphrodites. Fertilization is external,
with gametes released into the water. Larvae with
bilateral symmetry swim freely before they settle to
the bottom and morph into the adult form with radial
symmetry. Starfish have amazing regenerative
powers. If a starfish were torn to pieces each piece
could regenerate to a complete starfish as long as it
contains a piece of the central body.
Starfish
Starfish occur in many colors and may have more
than 5 arms. They live on the ocean bottom and are
carnivorous.
Brittle Stars
These are similar to starfish, but live in the tropical
areas on coral reefs and have longer arms. They
protect themselves by shedding one or more arms
which wriggles to distract predators while they
escape. These species are filter and detritus feeders.
Sea Urchins and Sand Dollars
Many of these are detritus feeders and grazers that
eat algae. They tend to stay hidden during the day
and come out of their burrows or crevices to feed at
night.
Sea Cucumbers
Most are detritus feeders and often cover the ocean
floor in herds of hundreds. Some can expel a sticky
substance that attaches to predators and
immobilizes them.
“The Vertebrate Animals”
Digestion
extracellular
“tube in tube system” with
accessory organs
(mouth, stomach, intestines, gall bladder,
liver, anus)
Gills, book lungs, tracheal tubes,
alveoli
Kidneys, nephrons, nephridia,
Excretion
glands and specializes cells
Open or Closed Circulatory
Transport
Systems, Heart(s)
Cephalized and Specialized Nerve
Systems with Motor and Sensory
Nervous System
divisions and enclosed brain and
spinal cord (notochord)
Sexual – separate sexes
Reproduction
Internal and external fertilization
Coelomate
Body Cavity
Segmented
Gas Exchange
Symmetry
Bilateral
Chordates
Chordates are animals possessing a dorsal hollow nerve
cord (which develops into a central nervous system), a
notochord (structure that protects the dorsal nerve cord),
Pharangeal Slits (structures which develop into gills in
aquatic chordates and inner ear and jaws of terrestrial
chordates) and a post – anal tail (which is present in the
embryonic stage of all chordates)
Almost every species belonging to Phylum Chordata is a
Vertebrate. Vertebrates are chordates that possess a
brain enclosed by a skull and a spinal cord enclosed by bone
(vertebrae) or cartilage.
Chordates typically have cephalized and specialized
nervous systems (with sensory and motor nerve networks)
in order to coordinate their complex organ systems and
movements.
Most Chordate species possess some form of internal
skeletal structure
Chordates have developed more complex respiratory and
circulatory systems in order to deliver oxygen and nutrients
to their larger organ systems.
Some chordates are ectothermic (their internal body
temperature varies depending on the surrounding
temperature) others are endothermic (they can use heat
produced by internal metabolic reactions to maintain a
constant body temperature)
Phylum Chordata is divided into five major classes:
Bony Fish Class:
Also called “Osteichtyes”, this class includes almost
all fish species. Fish display the following
characteristics:
• Aquatic
• Cold-blooded (ectothermic)
• covered with wet and slimy scales
• Streamlined for easy movement through water
• Fins for balance and to control movement
• Gills for breathing
• External fertilization
Reptiles:
Reptiles display the following characteristics:
• Cold-blooded (ectothermic)
• Body covered with dry, hard scales
• Live on land
• Breathe with lungs
• Internal fertilization; lay shelled eggs
• Includes lizards, snakes, turtles, crocodiles
Amphibians:
Organisms that spend at least part of their life (early
stages) in the water. Amphibian Characteristics
include:
• Cold-blooded (ectothermic)
• Moist, scaleless skin
• Limbs present
– tetrapods
• Larvae (tadpoles) use gills for breathing; adults
use lungs
• External fertilization
Birds:
Also called “aves”, characteristics of this class of
chordates include:
• Warm-blooded (endothermic)
• feathers
• wings
• Beak for feeding
• Lungs for breathing
• Internal fertilization; lay shelled eggs
• Hollow bones
Mammals:
Mammalian characteristics include:
• Warm-blooded (endothermic)
• Hairs on skin
• Females have mammary glands for producing
milk
• Lungs for breathing
• Diaphragm present
• Internal fertilization; embryos develop inside
mothers’ bodies