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ANIMAL NOTES
ANIMALS: Ch. 27-36 (Human Systems 37-43—covered in previous notes)
Introduction to Animals
Recall that members of the Kingdom Animalia are eukaryotic, multicellular heterotrophs with no cell walls. In
addition, animals are motile, diploid, and reproduce sexually. Animals all go through a blastula stage of
development and their cells are organized into tissues.
Evolution
As animals evolved, their general body plans changed. The most primitive animals today are sponges.
Sponges do not have a body plan – they are asymmetrical. There are 2 extant groups of animals with radial
symmetry, the cnidarians, commonly called jellyfish, corals, and anemones, and ctenophores or comb jellies. As
animals developed a head (cephalization) and limbs for predatory life-styles, bilateral symmetry became the
rule. All other groups or phyla have bilateral symmetry at some point in their life cycle.
Another change that occurred involves the body cavity common to most animals. The cavity is called a
coelom. If you imagine the skin and muscle of your torso forming a tube, and your digestive tract forming
another tube running through the much larger tube, the space between (where all your organs are) is a true
coelom. Scientists believe that having a coelom is the “primitive” or original condition, and that animals that
have a pseudocoelom (more later) or that lack a coelom (acoelomate) lost the coelom due to an advantage
given by the different body plan (an adaptation). Only organisms with bilateral symmetry are described as
having a coelom condition. The term does not apply to asymmetric or radially symmetrical organisms.
Segmentation is also an evolutionary trait common in the animal kingdom. Many invertebrates have
easily observable segmentation – annelids (earthworms), insects (abdomen & caterpillars), and crustaceans
(lobster tail). Vertebrates show remnants of segmentation during development. Blocks of muscles called
somites are visible in embryos, and even in the adult the vertebrae are reminiscent of segments. Segments by
definition are repeating sections of the body that contain structures of “every system”. However, they are
connected by the nervous and circulatory systems, and provide means for macroevolution. When a small
change occurs to an existing segment, a new type of segment with a new function will develop and can lead to
new species. Specialization of segments includes feeding and reproduction.
Structure and Function
We are going to address structure and function as one topic because the two are inextricably linked,
each reflecting the other. In science, the study of structure is called anatomy while the study of function is
called physiology.
Digestion
Digestion can occur intracellularly (food is brought inside a cell and digestion takes place with enzymes
like those in lysosomes), such as is found in sponges. Digestion can also occur extracellularly (enzymes are
secreted by the cells to break down the food into nutrients that can be absorbed into the cells). Extracellular
digestion can involve gastrovascular cavities, incomplete (2-way), or complete (1-way) digestive systems.
Gastrovascular cavities are found in many organisms including jellyfish. Incomplete digestive systems have a
single opening through which food enters the body and undigested waste exits. Complete digestive systems
(also called alimentary canals) have separate openings for taking in food (mouth) and expelling waste (anus).
Respiration
Respiration occurs across a moist membrane. In the process of respiration, oxygen and carbon dioxide
are exchanged. The simplest organisms respire by diffusion of the gases across membranes (think “skin”), such
as in flatworms, jellyfish, and amphibians. More complex organisms have a variety of structures for respiration,
including gills, book lungs, parapodia, and tracheae. Vertebrates rely primarily on gills (outpocketings of the
body, usually found only in aquatic organisms) or lungs (inpocketings of the body, which allowed organisms to
transition to a terrestrial lifestyle).
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Circulation
The simplest organisms lack a circulatory system because all molecules move from cell to cell by
diffusion. Many invertebrates have open circulatory systems which lack vessels (veins, arteries, and capillaries).
Instead, blood and interstitial fluids mix and bathe the internal tissues, carrying nutrients and oxygen and
removing waste. Some invertebrates and all vertebrates have closed circulatory systems in which the blood is
confined to the veins, arteries, and capillaries. In a closed circulatory system, the blood is kept separate from
the interstitial fluid.
Nervous Conduction
Sponges are the only group of animals that have no nerve cells (neurons). The simplest organisms do
not have nervous “systems”, but just unconnected cells. A more complex arrangement of neurons is called a
nerve net. This web of nerve cells is all connected but there is little coordination. Bilaterally symmetric animals
have ganglia – clusters of neurons that control regions of the body - creating coordination. As anterior ganglia
became larger and more complex (cephalization), central nervous systems including a brain and spinal cord
evolved.
Support & Locomotion
There are three types of skeletons found in the animal kingdom. The simplest organisms have a
hydrostatic skeleton, in which the coelom provides a stiff pocket of fluid for muscles to push against. Other
organisms have exoskeletons, such as the chitin on the outer coverings of arthropods and shells in the
mollusks. The most complex, including all vertebrates, have endoskeletons. Vertebrate endoskeletons are
composed of cartilage and bone. In addition to protection, skeletons provide a surface for muscle attachment,
allowing animals to be motile.
Excretion
Like circulatory and respiratory systems, many organisms lack excretory systems when diffusion out of
the body is sufficient to remove nitrogenous waste and carbon dioxide. The development of excretory systems
coincides with the needs of an organism to osmoregulate (maintain homeostasis in its water levels in blood,
interstitial fluid, and cytoplasm). The simplest excretory structures are called protonephridia. Protonephridia
(flame cells) are common in flatworms and a few other organisms and function more in osmoregulation than in
removing nitrogenous waste (ammonia produced in the breakdown of proteins). Metanephridia and Malphigian
tubules are a little more advanced in both structure and function, aiding animals in conserving water while
flushing toxins (ammonia) from their bodies. The most complex, found in vertebrates, are the kidneys. The
functional unit of the kidney is the nephron. The nephron functions to concentrate urea and salt while
conserving as much water as possible. The type of nitrogenous waste excreted varies among groups.
Organisms that are primarily aquatic and have shell-less eggs, such as fish and amphibians, can rely on the
diffusion of ammonia out of their bodies. In animals that have shelled eggs and for whom water conservation is
a problem, uric acid (a thick white paste) is excreted. Mammals produce urea, which is secreted in a solution
commonly called urine. Mammals can vary the concentration of urine depending on their water conservation
needs.
Reproduction
Many animals can reproduce asexually. Gemmules, fragmentation, and regeneration, as well as
budding and parthenogenesis, are all means of asexual reproduction. All animals that can reproduce asexually
(resulting in genetically identical organisms), can also reproduce sexually. Recall that sexual reproduction
involves the fusion of gametes created in meiosis resulting in genetic variation. Sexual reproduction in some
animals involves an exchange of sperm that is then used to fertilize eggs in each organism. Animals that are
slow moving or rarely encounter other members of the same species are often hermaphroditic. An animal that
is hermaphroditic can produce both eggs and sperm. Fertilization can also be external or internal. In external
fertilization, most common in aquatic species, the gametes are shed into the environment where they fuse into
the zygote. Internal fertilization occurs when sperm is deposited in the female reproductive tract where the
zygote is formed. If an animal lays a shelled egg or gives live birth, fertilization must be internal.
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Below is a summary of the most common animal phyla.
Invertebrate Animals
Phylum
Porifera
Common Name
Common Examples
sponges
marine sponges
Grantia
Cnidaria
cnidarians
jellyfish; Aurelia; coral;
anemones; Hydra;
Portuguese-man-o-war;
Obelia
Platyhelminthes
flatworms
flatworms; Planaria;
tapeworms; flukes
Nematoda
roundworms
Caenorhabditis elegans;
nematodes; Ascaris;
Trichinella; pinworms;
hookworms
snails, slugs, oysters,
mussels, clams, octopus,
squid, nautilus, cuttlefish
Mollusca
mollusks
Annelida
segmented
worms
earthworms; polychaete
worms; leeches
Arthropoda
arthropods
Echinodermata
echinoderms
Chordata
chordates
Arachnids (spiders, ticks,
mites, scorpions);
insects; centipedes,
millipedes; crustaceans
(lobsters, shrimp, krill,
barnacles, crayfish,
copepods, crabs,
Daphnia, pill bugs)
starfish, sea cucumbers,
brittle stars, sea lilies,
sea urchins, feather
stars, sand dollars
tunicates, lancelets;
vertebrates
Distinguishing Description
sessile; lack tissues (therefore no organs or
systems); asymmetrical; often hermaphroditic;
spicules make up the internal skeleton
sessile polyps & motile medusa; radial
symmetry; have 2 layers of tissue but no
organs/systems; gastrovascular cavity;
hydrostatic skeleton; cnidocytes with
nematocysts
motile; free-living or parasitic; true tissues &
simple organ systems; bilateral symmetry;
acoelomate; protonephridia (flame cells);
incomplete digestive system; proglottids
Motile; free-living or parasitic; true tissues &
simple systems; bilateral symmetry;
pseudocoelomate; complete digestive system
motile; organ systems; bilateral symmetry;
coelomate; complete digestive system; visceral
mass; mantle; foot; shells; radula; nephridia;
heart & open circulatory system (closed in
octopus & squid); gills; some hermaphroditic
motile; organ systems; bilateral symmetry;
coelomate; hydrostatic skeleton; complete
digestive system with organs-crop, gizzard,
stomach, intestine; cerebral ganglia;
segmentation; closed circulatory system;
parapodia; setae; some hermaphroditic;
earthworms are ecologically important as
decomposers/detritivores that concentrate the
nutrients in soil & in aerating the soil
motile; organ systems; bilateral symmetry;
coelomate; exoskeleton of chitin; complete
digestive system with organs; segmentation;
open circulatory system; jointed appendages;
multiple & varied mouth appendages; brain;
ecdysis (molting); Malpighian tubules;
complete & incomplete metamorphosis
motile; water-vascular system; tube feet;
bilateral symmetry in larvae, radial in adult;
coelomate; deuterostomes; endoskeleton of
ossicles; skin gills
notochord, dorsal hollow nerve cord,
pharyngeal gill slits, postanal tail (also motile,
bilaterally symmetrical, coelomate,
deuterostomes)
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Classes
Agnatha
Chondrichthyes
Osteichthyes
Amphibia
Reptilia
Aves
Mammalia
Subphylum Vertebrata (Vertebrate Animals)
Common Name
Common Examples
Distinguishing Description
jawless fish
hagfish & lampreys
lack jaws; hagfish are not truly vertebrates;
lampreys are freshwater fish parasites while
hagfish are marine detritivores
cartilaginous
sharks, skates, rays
jaws; skeletons of cartilage with very little
fish
ossification (true bone); mostly predators, a
few filter feeders (whale shark, some rays);
gills; mostly internal fertilization; some
oviparous, ovoviviparous, viviparous; 2
chambered heart; kidney; mostly ectothermic;
lateral line
bony fish
guppies, goldfish, tilapia,
jaws; endoskeletons are ossified at maturity;
flounder, eels, seahorses,
feeding varies; gills; external fertilization &
etc
internal fertilization; oviparous, ovoviviparous,
viviparous (mostly oviparous – lay eggs); 2
ray-finned fishes, lobechambered heart; kidney; mostly ectothermic;
finned fishes, lungfish
lateral line; swim bladder
amphibians
frogs, toads, salamanders, bony endoskeleton; metamorphosis; gills,
newts, & caecilians
primitive lungs, moist skin; oviparous with
external fertilization; 3 chambered heart;
kidney; ectothermic; tympanic membrane
reptiles
lizards, snakes, crocodiles, bony endoskeleton; lungs; scales; oviparous,
turtles, tuataras
ovoviviparous with internal fertilization; 3
chambered heart (4-chambered in crocodiles);
generally ectothermic; kidney; uric acid;
amniotic egg with leathery shell
birds
ostriches, emus, parrots,
bony endoskeletons with adaptations for flight
eagles, sparrows,
including wings, hollow bones, keel; feathers;
flamingos, hummingbirds,
oviparous with internal fertilization; 4owls, etc
chambered heart; endothermic; kidney; uric
acid; amniotic egg with hard shell (calcerous
shell); respiratory system modified with air
sacs to increase oxygenation at high altitudes;
beaks and feet show adaptations for specific
diets/ niches
mammals
Monotremes – platypus &
Bony endoskeletons; hair; viviparous with
echidna
internal fertilization (except the monotremes
Marsupials – opossum,
which are oviparous); mammary glands
kangaroos, koalas, etc
produce milk; teeth vary with diet;
Placentals (eutherians) –
endothermic; 4-chambered heart; kidneys
bats, whales, seals, bears, produce urine containing urea (made in the
dogs, cats, raccoons, rats, liver); lungs; internal fertilization; marsupials
deer, horses, cows,
have a marsupium (pouch) containing teats for
rabbits, manatees,
nursing; eutherians have a placenta
elephants, monkeys &
apes
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Animal Behavior—Ch. 36
Evolution of Behavior
behavior – an action or series of actions performed by an animal in response to a stimulus
stimulus – something in the environment (sound, smell, color, another organism), or related to internal state of
the organism (hunger, cold)
The study of behavior (ethology) focuses on:
How – how is a behavior triggered, controlled, and performed
Why – concern the reasons a behavior exists and are really questions about the evolution of a behavior;
answers the question what are the benefits of a behavior
natural selection – evolutionary theory that states that traits are favored that will improve the likelihood
that an individual will survive to reproduce; over time, this will result in a change in genotypic or phenotypic
frequencies in a population
- natural selection can answer the “why” of behavior – because it provides that animal an advantage that
leads to an increase in survival and reproduction
Behavior can also be intentional or random. Intentional movement in response to a stimulus is called taxis.
The random movements sometimes produced are called kinesis.
taxis – response to a stimulus in which an organism move toward (positive) or away (negative) from the
stimulus; ex) animals may move toward a scent of prey
kinesis – undirected, random movement in response to a stimulus; ex) a herd may scatter in response to the
presence of a predator; pillbugs may move randomly and quickly when encountering an environment that is too
dry, but more slowly (but still randomly) when an environment is wet
innate behavior – genetically programmed behavior; instinct; typically little to no variation in the behavior and
does not require teaching; fixed action pattern
learning – development of behaviors through experience
habituation – animal learns to ignore a frequent, harmless stimulus; for humans, things like the TV in the
background
classical conditioning – complex learning by association
operant conditioning – trial-and-error learning – when animals learn that performing a certain action will result
in a reward or punishment
reasoning – ability to analyze a problem and think of a possible solution; uses experience to develop an insight
into how to solve new problem
imprinting – learning that can occur only during a specific period early in the life of an animal and cannot be
changed once it occurs
Types of Behavior
Behavior is classified into many different categories, including
foraging – locate, obtain and consume food
migratory – move to a more suitable environment as seasons change
defensive – protect from predators
territorial – protect a resource for exclusive use
courtship – attract a mate
parental – ensure survival of young
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Invertebrate Animal Notes (Ch. 28-31)
Introductory Vocabulary
Invertebrate – animal without a backbone
Coelom – fluid-filled space between body wall and intestine
Cephalization – sensory organs concentrated at the anterior end of the organism
Hermaphrodite – animals with both ovaries and testes
Sessile – nonmotile; animal that doesn’t move
Open circulatory system – vessels empty into body spaces called sinuses
Closed circulatory system – blood never leaves vessels as it flows through the body
Notochord – stiff rod found in chordates that becomes the vertebral column in vertebrates
Dorsal nerve cord – bundle of nervous tissue found in chordates that becomes the spinal cord in vertebrates
Pharyngeal slits – openings in the pharynx found in chordates that give rise to many structures in vertebrates
Kingdom Animalia: 8 Invertebrate phyla:
1.
2.
3.
4.
5.
6.
7.
8.
Porifera -sponges
Cnidaria-sea anemones, coral and jelly fish
Platyhelminthes -flatworms (planaria, flukes, tapeworms)
Nematoda -roundworms
Mollusca-slugs, snails, “seashell animals”, octopii and squid
Annelida – segmented worms (marine worms, earthworms & leeches)
Arthropoda – insects, arachnids & crustaceans
Echinodermata – starfish, sand dollars, sea urchins, & sea cucumbers
Phylum Porifera – ex. SPONGES
–Multicellular; no true tissue; asymmetric; sessile
–spongin- protein fibers for structure; spicules for skeleton
–filter feeders
–asexual reproduction - fragmentation
–sexual reproduction - hermaphroditic
•External fertilization – shed gametes in water
Phylum Cnidaria - ex. jellyfish, Portuguese man-of-war, sea anemone, coral
•Radial symmetry; true tissues; sessile and/or motile
•Cnidocytes - stinging barbs to capture prey
•Tentacles to bring prey into gastrovascular cavity
 Two body forms
–Polyp – sessile with mouth dorsal
–Medusa – motile with mouth ventral (adult)
•Asexual reproduction - budding
•Sexual reproduction - external fertilization
Phylum Platyhelminthes – ex. flatworms (planaria, tapeworms, flukes)
-Bilateral symmetry; cephalization; acoelomate; organs; some free living, many parasitic
-Nervous system: ganglia and nerve chords
-Digestive system: two-way digestive tract with common mouth/anus;
gastrovascular cavity
-Respiratory & Circulatory system: diffusion
-Reproductive system:
-Sexual – internal fertilization; hermaphroditic; lay eggs
-Asexual - fragmentation
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Phylum Nematoda – ex. roundworms (hookworms, pinworms)
-pseudocoelomate; hydrostatic skeleton
-one-way digestive system with separate mouth/anus
-Respiration and circulation by diffusion
-Reproduction – sexual; complex life-cycle with multiple hosts
-Most are free–living predators in the soil
-Some are parasitic; hookworms, pinworms, Trichinella
Phylum Mollusca – ex. snails, slugs, clams, oysters,
mussels, squid, octopus
•Coelomate; bilateral symmetry; organs; exoskeleton (shell)
•3-part body plan
•cephalization
•open circulatory system
•one-way digestive system
•Respiration – gills, mantle cavity, and/or diffusion across skin
•Reproduce sexually; many hermaphroditic
Phylum Annelida – ex. earthworms, leeches, marine worms
•Segmentation – separated by septa; each segment has organs
of each major system
•Cephalization – including cerebral ganglia
•Ventral nerve cord
•Coelom – hydrostatic skeleton
•Organ systems
Phylum Arthropoda ex. millipedes, centipedes, insects, spiders, crustaceans
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largest and most diverse phylum; includes insects, crustaceans, spider
segmented bodies – head, thorax, & abdomen or cephalothorax & abdomen; segmentation
apparent on abdomen
• Jointed appendages (3, 4 or 5 pairs of walking legs plus assorted other specialized
appendages)
• exoskeleton of chitin
 Respiration: spiracles into trachea; gills; book lungs
 Excretion through Malpighian tubules
 complex muscular system, ventral nerve cord & brain, open circulatory system,compound eyes
 ecdysis (molting)
Millipedes – 2 pairs of legs per segment; 1 pair antennae
- herbivores or detritivores, but can be really smelly!
Centipedes – 1 pair of legs per segment; 1 pair antennae
- predators with jaws
Insects – 3 body regions: head, thorax, abdomen
- 3 pairs of legs attached to thorax
- exoskeleton of chitin
- jaws (mandibles)modified for particular feeding method
- wings are extensions of the exoskeleton; 0, 1 or 2 pairs
- 1 pair of antennae
- compound eyes
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Arachnids – spiders, scorpions, ticks, & mites
•Chelicerae – mouthparts modified into pincers or fangs
•cephalothorax & abdomen
•4 pairs of walking legs
•no antennae
•simple eyes
•Spinnerets & silk glands in spiders
•book lungs in spiders
•Predators that consume liquified food
•Distantly related to horseshoe crabs
Crustaceans
Ecologically important – copepods & krill are planktonic crustaceans that form the basis of many marine
food chains
Crabs, lobsters, shrimp, & crayfish are other well-known crustaceans called decapods – “10 feet”
First pair of walking legs often modified into chelipeds (pincers)
2 pair of antennae
compound eyes
sexual reproduction
Cephalothorax covered by carapace
Small appendages on abdomen of some called swimmerets
Barnacles are sessile crustaceans
Pill bugs (isopods) are terrestrial crustaceans with gills
Phylum Echinodermata – ex. starfish, sand dollar, sea cucumber, etc.
•Only live in salt water (oceans)
•Five-part radial symmetry in adults; larvae are bilaterally symmetrical
•Hard, bumpy, spiny endoskeleton composed of ossicles
•water vascular system with 5 rows of tube feet that aid them in movement, gas exchange, food capture and
waste excretion.
•Skin gills increase respiratory surface area & function in excretion
•Feeding in starfish involves everting stomach out of mouth, digesting prey outside of body, and then
pulling the digested material into the body; other echinoderms tend to be filter feeds or detritivores
Ex: starfish, sand dollar, sea cucumber, sea urchin, sea biscuit, brittle stars, sea lilies, sea daisies, sea
pens, feather stars
Invertebrate Chordates—ex. tunicate and lancelet
4 characteristics of all chordates:
*Notochord
*Dorsal hollow nerve chord
*Pharyngeal gill slits
*Postanal tail
Invertebrate chordates include tunicates & lancelets; all other chordates are vertebrates
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Vertebrate Animal Notes (Ch. 32-35)
DOMAIN- Eukarya
KINGDOM- Animalia
PHYLUM- Chordata
SUBPHYLUM- Vertebrata
CLASS- 7 different
Phylum Chordata
Recall that ALL vertebrates are chordates.
Phylum Chordata includes the lancelets and tunicates (invertebrate chordates) as well as the
vertebrates
All chordates have:
Characteristics of all Vertebrates
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Endoskeleton with a backbone for support of a dorsal nerve cord & muscle attachment
Distinct skull/cephalization
Bilateral symmetry
2 pairs of jointed appendages
Coelom
Closed circulatory system & chambered heart
Major Groups of Vertebrates
•Fish – aquatic tetrapods with scales, gills, & __2__ chambered hearts
•Agnathans – jawless fishes – hagfish and lampreys
•Chondrichthyes – cartilaginous fish - sharks & rays
•Osteichthyes – bony fish – mahi-mahi, tilapia, halibut, puffer fish, tetras, guppies
•Amphibians – semi aquatic tetrapods with split lives and __3__ chambered hearts
• frogs and toads, salamanders and newts, caecilians
•Reptiles – terrestrial amniote tetrapods with scales & lungs & 3ish to 4 chambered hearts
• lizards and snakes, turtles and tortoises, alligators, crocodiles, and related species
•Birds – terrestrial amniote tetrapods with feathers & lungs & __4__ chambered hearts
• ostriches, emus, kiwis, jays, sparrows, crows, ducks, swans, geese, eagles, falcons, hawks, penguins
•Mammals – terrestrial (most) amniote tetrapods with lungs, hair, and mammary glands & _4_ chambered
hearts
•Monotremes – echidna and platypus
•Marsupials – koala, kangaroo, opossum
•Placentals – humans, bears, tigers, giraffes, deer, pigs, dogs, cats, raccoons, squirrels, whales,
walruses, manatees, etc
Fish Vocabulary
•Gill – respiratory structure that uses countercurrent exchange to extract oxygen from water
•Lateral line - a row of microscopic organs sensitive to pressure changes, can detect low frequency vibrations.
•Swim bladder – internal, air-filled sac that acts as an organ for buoyancy in bony fish; sharks have oils in their
livers to help them remain buoyant
•Reproduction
 External fertilization – release of gametes to the environment where fertilization takes place; bony fish
 Internal fertilization– deposition of sperm in the female reproductive tract where fertilization takes
place; sharks
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Hermaphrodite – some organisms are capable of producing both male and female gametes; few are
capable of self-fertilization; most exchange sperm; evolutionary adaptation for solitary and slow-moving
or sessile organisms
Ovoviviparous = eggs are fertilized inside the parent and hatch inside the parent and are born live
Oviparous = eggs are laid in a nest or in the ground and hatch
Viviparous = internal fertilization with live born young (as soon as the egg is fertilized, it becomes an
embryo and develops as a fetus).
Class Agnatha—Ex. Hagfish and lampreys
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-jawless & finless
-Skeleton of cartilage
-Reproduce sexually
-Gills
-_2_ Chambered Heart
oviparous
Lamprey – an ectoparasite
Hagfish – a detritivore
Class Chondrichthyes – Ex. sharks and rays
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-Endoskeleton made of cartilage
-_paired fins
-Jaws
_2_ chambered heart
-Well-developed sense of sight and smell, most carnivores
-lateral line system (for sensing pressure changes – vibrations - in water); whole body acts as an “ear”
-unique scales; teeth may be modified scales
-Oviparous, ovoviviparous, and a few are viviparous
-Internal fertilization using claspers to deposit sperm in female reproductive tract
Class Osteichthyes—Ex.Tuna, perch, bass, clown fish, eels, seahorses, goldfish, catfish, etc….

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One of the most successful groups on Earth – ever!
-endoskeleton made of bones
-Swim bladder
-Usually, external fertilization & oviparous (think caviar)
-lateral line system
-scales different from those in sharks
- 2 chambered heart (all fish!)
-Water balance important; some fish excrete salt through their gills, others very watery nitrogenous
waste using kidneys
Amphibian Vocabulary
ectotherm – organism that must gain (or lose) heat from the environment to maintain body temperature;
metabolism is NOT sufficient to heat the body; most invertebrates, fish, amphibians, & reptiles
endotherm – organism that maintains a stable body temperature through metabolism; few reptiles, most birds
and mammals, insects
metamorphosis – change from a sexually immature stage to a sexually mature stage in the life cycle; involves
change in body structure and niche; ex) tadpoles are herbivorous, aquatic larvae with gills and no limbs that
change into carnivorous, terrestrial adult frogs with lungs and 4 limbs
lungs – internal respiratory organs that exchange gases across a membrane surface, usually in conjunction with
the circulatory system
cloaca – common opening to the outside of the body through which fecal material, nitrogenous waste and
gametes pass; common to amphibians, reptiles, and birds
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Class Amphibia – Ex. Frogs, toads, salamanders, and newts
-Ectotherms
-Need water for breeding
-Metamorphosis (tadpole to frog)
-Gas exchange through moist skin & mouth; primitive balloon-like lungs
-External fertilization
-Oviparous
-__3__-chambered heart
-Many have chromatophores in the skin for coloration, as well as poison glands for defense
-Nitrogenous waste varies – aquatic habitat -dilute urine; terrestrial, concentrated urine
Reptile Vocabulary
Amniotic egg – adaptation to terrestrial life that results in a water-proof egg with extra-embryonic membranes
that aid in the vital functions of a living organism
bask – behavioral adaptation of ectotherms to increase body heat; involves moving to locations where more
radiant energy (such as from the sun or warm rocks) is available for absorption
Class Reptilia - turtles, snakes & lizards, crocodiles
-ectotherms – bask and hide to regulate temperature*
-Scaly, waterproof skin
-Respire through lungs only**(turtles can through cloaca)
-Internal fertilization
-Oviparous, ovoviviparous, viviparous (depending on species)
- 3 or 4 chambered heart
-Nitrogenous waste is a paste rather than a liquid for water conservation; uric acid
Extinct reptiles include dinosaurs and pterosaurs, which dominated the Earth during the Triassic period
Crocodilia – alligators and crocodiles (caiman, and other related species)
•Adapted for aquatic life with upturned nostrils and eyes on top of head
• *endothermic
•4-chambered heart
•Related to feathered reptiles (birds)
Class Aves - Birds
-_Endothermic
-__4__chambered heart
-Internal fertilization
-Oviparous
-Amniotic eggs with calcerous, hard shells
-Cloaca
-Nitrogenous waste paste-like for water conservation; uric acid
-Beaks and claws modified for specific niche
-Classified as reptiles by many taxonomists
-Digestive system modified for diet, including crop & gizzard
-Many modifications for flight:
-Only organism with feathers (modified scales)
for flight and insulation
-Hollow bones - make bird lightweight
-Front limbs modified into wings
-Air sacs to aid in breathing at high altitudes
-Unique muscle tissue for sustained, intense use
-Keel – modified breastbone for muscle attachment
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Mammal Vocabulary
Mammary gland – gland adapted to produce protein and fat rich nutrition for offspring during early
development
Hair – keratinous growth for insulation, camouflage, and display; made of same material as reptilian scales and
bird feathers
Class Mammalia – ex. humans, bears, pigs, horses, dogs, cats, whales, elephants, mice, koalas,
platypus
-Endothermic – hair and layer of fat aid in conserving heat
-**Hair – keratinous protein that aids in insulation
-**Mammary glands – produce milk to feed offspring
-Internal fertilization
-2 species of monotreme; oviparous
-Marsupials and placentals are viviparous
-Diaphragm for increased respiration & spongy lungs for increased surface area
-___4___-chambered heart
-Inner ear contains 3 bones for improved hearing
-Large brain; learn; Extended parental care
-Most effective kidney for water conservation; urea
**=unique to mammals, no other vertebrate animal possesses these
3 categories of mammals
1. Monotremes - mammals that lay eggs. Ex. platypus and echidna
mother produces milk which is excreted from glands on the abdomen and the babies lap up the milk or
drink it off the fur of the mother;
2. Marsupials - embryo develops in a uterus with a placenta. Ex. koala, kangaroo, sugar glider, opossum
Immature fetus is born into a pouch called a marsupium.
Young develop in marsupium, attached to a teat, until much more mature.
All marsupials live in Australia with the exception of the opossum, which can be found in the Americas.
3.Placentals
Placental mammals develop in a uterus attached to a placenta until at a comparably advanced stage of
development. Ex. Humans, cats, horses, monkeys, rats, whales
Widespread on earth – found in every major biome, including marine, arctic, and tundra.
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