These Handouts have been modified from their original versions by Mr. Jewett. Highlights
have been added for important information for the test, and some citations and less-important
information has been removed, to shorten the document.
1. General information
a) Platyhelminthes means flat worms.
Annelida means segmented worms, their body is composed of segments.
Nematode means round worm.
b) Platyhelminthes have bilateral symmetry along their length.
Annelida generally have bilateral symmetry along their length of their body.
2. The place of the phylum in the evolutionary tree
a) Most recent common ancestor of bilaterallians lioved 575 million years ago.
b) Platyhelminthes are most closely related to Molluscs.
c) Annelida are most closely related to Molluscs.
d) Nematode are most closely related to Arthropods.
3. Derived characteristics
a) Platyhelminthes b) Annelida
- First animals with organs and systems - segments and division of the head, body and
- Three layers: ectoderm, endoderm, anal part.
mesoderm - Skin-muscle sac is developed.
- First animals with bilateral symmetry - True gastrovascular cavity with walls. There
- Enables wandering and swimming in one are segments. There is first respiratory
direction system. They have gills. They are changed
- There are front and back sides parapods.
- skin-muscle sack covered with epithel and - There is a circulatory system. There are ring
muscle fibers. It surrounds a gastrovascular and straight blood vessels.
cavity, in which there are parenchyma cells. - There is excretory system metanephridia.
They store nutrients and are support. Two tubules in each segment.
- Closed digestive system develops - The nervous system has a brain and cords.
- There is an excretory system. There are
excretory cells protonephridia (ciliated
- There is a reproductive system. They are
generally hermaphrodites. There is a direct
development. Parasites have metamorphosis.
- The nervous system is of ganglia.
a) Platyhelminthes b) Annelida
- Sexual reproduction is a common way of - Asexual reproduction happens again through
reproduction in all groups of the process of fission (splitting).
platyhelminthes. - The posterior part of the body breaks off and
- Most of them are hermaphrodites, meaning a new individual is formed from each part
that they have both male and female during splitting.
reproductive organs. - The annelids that reproduce sexually can be
- They can cross – fertilize or self – fertilize either hermaphrodites or gonochorists (they
- The worm is ready to fertilize when a have distinctive genders).
whitish band, called clitellum is formed - The hermaphrodites like the earthworms
around its neck. meet regularly throughout the year and
- Asexual reproduction is called fission copulate while their bodies point in different
- Parthenogenesis – reproduction without - Sperm is transferred from the male pore to
fertilization the other worm
- A similar process happens when two
5. Life cycle
Platyhelminthes and Annelida
The flat and the segmented worms have direct or indirect life cycles. The direct one follows the fission
reproduction, while the indirect one has several stages which usually follow the sexual reproduction.
The worms that reproduce sexually go through the following stages:
1. When the copulation ends, the clitellum produces a ring which surrounds the eggs and hardens into
2. From 2 weeks to 3 months the eggs start hatching and small worms emerge.
3. The third stage is called juvenile. During this stage the worm is in the form of a larva.
4. The young worm is smaller than the adult worm and it does not have reproductive organs until they
reach a particular age (12 months for the earthworms).
6. Digestive System
- gastrovascular cavity, which distributes digested food to cells lining it. They have subbranches
that make extensive areas.
- Consists of mouth, front and middle intestine, appendix. [one hole – jj]
- It is closed, and the indigested food is rejected.
- There are digestive juices inside the body.
- In parasites the digestive system may not be developed. They eat microorganisms. There are
parasites who feed on another organism.
- It is open.
- There are mouth, front, middle, back intestine, appendix and anus. [two holes – jj]
- They eat microorganisms. There are parasites, endoparasites and ectoparasites.
7. Nervous System
• Two nerve knots ganglia • More complex
• Two nerve ventral cords • Cerebral ganglia around the mouth
• Branches • Nerve chain along the body
• There can be eye spots • Sense organs
8. Medicinal Leech
- Hirudo medicinalis
- It is Annelida, class Leeches.
- Lives in small fresh bodies of water.
- It reproduces by eggs, covering them with a cocoon.
- It goes out of the body of water and digs a hole and the cocoon is there.
- After 6-8 weeks the eggs hatch, and the new leeches go in the water.
- They mature in the third year.
- It may reach 30 centimeters.
- They don’t have parapods.
- It is a parasite sucks blood from organisms.
- It is used in medicine to drain blood that clot from an injury and internal bruise.
- It makes an incision and releases hirudin - a chemical used to prevent clotting. It is used to
dissolve blood clots.
9. Red Californian Worm
- Hybrid of the Eisenia foetida worm from the Annelide phylum which was produced in
1956 in the University of California
- Live in the soil since the direct sun light makes them die in a few minutes
- The best temperatures for reproduction are between 14o and 17o
- Length up to 10 cm., diameter 3-5 mm
- Eat organic wastes and especially feces
- Produce natural organic fertilizer which contains very high amounts of minerals
- Special farms with Red Californian worms where this natural fertilizer is produced
- Move as the typical segmented worms – with parapodi
- The stages of life are egg, cocoon, larva and adult worm
- Scientific name is Taenia solium
- Life Cycle:
a) Pork eating food or drinking water contaminated with eggs from human feces
b) the larva in the egg - oncospheres hatch in the pig's small intestine, penetrate the gut wall and
move to a number of areas inside the animal
c) This oncosphere quickly changes into a fluid-filled bladder form called a cysticercus
d) Cysticerci become visible within 2 to 4 weeks, and reach their full size in 60 to 70 days
e) Passed from swine to humans via raw pork or insufficiently cured pork or ham
f) The tapeworm attaches to the human intestine by its "head," called a scolex.
g) The tapeworm grows to a length of 2 to 7 meters in 5 to 12 weeks.
h) Most of the tapeworm consists of a chain of 700 to 1,000 segments, those segment packed with
up to 40,000 eggs, these egg-filled segments are passed in the feces
a) Tapeworms can be found everywhere on land and in water where vertebrates live
b) Adult tapeworms live in vertebrates intestines of humans and animals
- What do they eat:
a) they often hook for attaching to the liver or digestive tract of the host
b) when they are attached they absorb the nutrients released by digestion in the hosts intestines,
through their body wall
- Ecological role/niche:
a) the pork tapeworms are very bad for the living organisms since they are parasites
b) they enter the body and may cost serious problems with the vertebrates in the human and
- Locomotion: the end of the tapeworms is armed with sackers and hooks which the worm uses
to attach itself to the inner organs and moves by that way
11. Role of worms in human’s life
a) Parasites in host organisms like humans and usually some of the stages of their life
develop in host organisms. Their parasitic life usually makes the host organism ill
b) At the end of the food chain → The worms use organic wastes to produce mineral rich
elements which feed the ground and help the growth of plants. Thus the worms are indirectly
involved in producing the food that humans eat and from which people take the minerals and
vitamins needed for the proper function of their organisms.
For 1,5 years feeding in laboratory a gigantic medical leech was grown 44 centimeters.
WORMS Crossword by Dimana, Kristian, Alan, 10-2
1. What do worms eat in order to produce mineral rich element?
4. What two things has the nervous system of annelida worms has? (the answer includes
5. How is it called when a worm has male and female reproductive organs?
7. What is the second stage of life by the red Californian worm?
9. What produces a ring which surrounds the egg in the life cycle?
10. To what group are Platyhelminthes most closely?
11. After 6-8 weeks the eggs hatch, and the new ........ go in the water.
12. In which worm a gonochorists reproduction can be seen?
13. What does annelida has that the platyhelminthes worms don't have it?
14. What is the Latin name of the red californinan worm?
15. What is a name for a flat worm?
2. What surrounds the skin muscle of the Platyhelminthes worms?
3. Where can you find a tapeworm?
6. What does the medical leeches releases in order to prevent clotting?
8. What can they harm in the human body?
A Biodiversity Project
1. Scientific name
“Ichthyoid” – fish-like or hagfish and lampreys, similar to fish but not true fish
Ichthyology = from the Greek ἰχθυ, (ikhthu, fish) and λόγος (logos, reason), the scientific study of fish,
particularly in taxonomy, zoogeography, anatomy, systematics, and ecology. (15)
• Can be cartilaginous (sharks, rays) or bony (other). Hagfish are most primitive.
- Their skin is covered with scales.
- Their limbs have modified into fins.
- They have gills, instead of lungs.
- Heart is two-chambered
- * Bilateral symmetry
a. Evolution: Closely related are the Amphibians.
Domain: Eukarya; Kingdom: Animalia; Phylum: Chordata
b. Human/Fish Ancestor
The common ancestor of humans and fish probably is believed to contain only 12
chromosomes. By studying the genomes of fish and mammals, scientists were able to
determine that it lived in the Paleozoic era (about 450 million years ago). The ray-finned
fishes, which are the majority of fish known today, duplicated their genome shortly after the
separation of the t lineages of mammals and fish. (14)
- Ovoparity-- lay undeveloped eggs, external fertilization (90% of bony fish) or
internal fertilization (some sharks and rays)
- Ovoviviparity- internal development (without direct maternal nourishment)
-advanced at birth (most sharks + rays) or larval birth (some scorpeaniforms-rockfish)
- Viviparity - internal development (direct nourishment from mother) fully
advanced at birth
4. Gas, Food/Waste Exchange with Environment
A large number of fish exchange gases due to the gills positioned in either side of the pharynx
( the head). In the gills, which provide a large surface area for exchanging oxygen and carbon dioxide,
the process of respiration occurs. Through the gills, the blood picks up oxygen from the surrounding
water and distributes it through arteries that lead to all parts of the body. When the oxygen is used in
the body, it goes back to the heart and this path represents a relatively simple closed-circle circulatory
b. Food/Waste Exchange
Jaws allow fish to eat a wide variety of food, including plants and other organisms. The food is
being ingested through the mouth and broken down by digestive enzymes( which catalyze reactions),
then the available nutrients are absorbed. Organs such as the fish liver or the pancreas add digestive
enzymes to the food that travels through the digestive tract. After digestion, the process of excretion
logically follows. Most fish release their food wastes as ammonia. Some of the wastes are diffused
through the gills, blood wastes are filtered by the kidneys. (12)
Even thought the density of water is higher than that of air, fish still can move quickly
and smoothly. The skeleton of fish is one of the most complicated ones; it provides
framework for the movement. The muscles, which are 80% of the body, provide power. The
vertebral column acts as levers that operates the movement.
- The streamlined shape of the fish and a special slime fish excrete from their skin
minimizes the drag.
6. Fish Thermal Strategies
In general, fish are cold blooded. They derive their body heat from their environment and conform
its temperature. As water has a high heat capacity, it is able to easily suck any excess heat out of a fish
and into the environment.
a. Ectothermic: fish derive their heat from the environment
Endothermic- ‘‘within- heating’’
b. Poikilothermic: fish conform to the heat in the environment
Some large, fast-swimming fish are not ectothermic. For instance, the tunas and mackerel
sharks can actually have core body temperatures ten to twenty degrees Celsius higher that the
surrounding water. They are endothermic and derive their body heat from their metabolism, but they
are still ploikiothermic; their body temperature may be higher than the surrounding water, but they still
conform to the temperature of the water, just 10-20 degrees above it. (12)
Why should they bother having an elevated body temperature?
To increase the speed of the fish. The higher the body temperature, the greater the muscular power.
Thirty degrees Celsius is the optimum temperature for muscular speed.
7. Class Chondrichthyes (Cartilaginous Fish)
Common Name: Whale Shark
Latin Name: Rhincodon typus
*The largest fish on earth (mouth = 1m- 1.5m, average lengh = 7-8m, biggest = 12-14m, weigth =
15-20 tones) (1,2,3).
Food: Even though the whale shark is the largest fish on Earth, they are known to be filter
feeders(2).It eats by sucking water with all the small animals in it such as: krills, crabs, planktons,
Habitat: Whale sharks live in warm seas
such as the tropical parts of the Atlantic,
Indian and the Pacific ocean (1,3) because these
oceans' water temperature on the surface
ranges between 20 and 27 0C (4) .
Reproduction: Whale sharks are viviparous
meaning they give birth to their offspring (3).
They give birth to around 300 small sharks at
the same time, each ranging from 0.55 to 0.6
m long (3,4) .
Life Cycle: Whale Sharks migrate following
its food (seasonal feeding). Usually their life is long as much as 100 years (3).
Locomotion: Known as slow swimmers, whale sharks move their whole body in order to move
through the water (in contrast, most sharks and fish move only their tails) (3).
Ecology: Human impact: whale sharks are easy to catch by fishermen because they swim at the
surface of the water (4) . A highly valued product in Taiwan and China (4)!
8. Class Osteichthyes (Bony Fish)
Common Name: Clown Fish
Latin Name: Amphiprion percula
* Unlike the whale shark, the clown fish is a very small animal with length ranging from 5 to 13
Habitat: lives near anemone which is a poisonous plant that lives at the sea bottom and eats fish (6)
. When another fish touches it, the plant omits its poison and kills the fish (6). Also they live in the
parts of the Indian and Pacific Ocean (7).
Food: Its source of food, as well as protection, is the anemone. The clown fish eats dead anemone,
parts of poisoned fish that the anemone does not eat and plankton (6).
Reproduction: Again the anemone plant is used for protection during the period of reproduction.
The male clown fish builds a nest near it which is the place where the numerous eggs are
put(between 100 and 1000) (7) . The eggs turn into small fish after about 4 to 5 days (7) . Clown fish
are known to be hermaphrodites (7).
Locomotion: Clown Fish move via fins. With them they change speed and direction. The clown
fish has 4 types of fins - dorsal and ventral (both used for balance), caudal (used to improve
forward movements), pectoral (used to navigate and change direction) fins (8).
Ecology: Clown fish are not threatened by human activity. It has a close relationship with
9. Class Agnatha (only two living species now- Fagfish and Lamprey)
Common Name: Hagfish (YES IT IS A FISH)
Latin Name: Myxine glutinosa
* Most primitive fish! It is between 0.4 and 0.6 m long (10). A jawless fish with cartilage skeleton.
Habitat: It lives in depths between 20 and 600 m(10). They prefer muddy sea bottoms(10).
They live primarily in the Atlantic Ocean near the coasts of America and Europe.
Food: They eat dead fish which drop on the bottom of the sea and worms(10).
Reproduction: Hagfish are able to reproduce only after they reach 25 to 28 cm (10). They have
both sexual organs, however, only one them (either the male or female) is fully developed (9) .
They reproduce by eggs- ranging from 19 to 30 for each reproduction (9).
Locomotion: Hagfish have no fins. They move by tails that resemble the sculls of a boat.
Ecology: Hagfish represent no treat for humans. Most hagfish are disgusting and that is why they
are not eaten. Yet there is one species kkomjangeo which is eaten in Korea (11).
10. Human- Fish Interactions
Fish is an important human and animal food source, which is ‘hunted’ in wild fisheries or in
‘farms’. They are also caught and raised by fish keepers and scientists, then exhibited in public
aquaria. Furthermore, fish have had an interesting culture role through the ages, serving as deities,
religious symbols, subjects of art and books. For instance, fish has religious significance in Hindu,
Jain, Buddhist, and Christian traditions (referring to feeding the multitude in the desert).
11. Fun facts
• If you keep a goldfish in a dark room, it will eventually turn white.
• A shark can detect one part of blood in 100 million parts of water.
• The most poisonous fish in the world is the Stone fish.
• The largest known fish in the sea is the Whale Shark. It weighs up to 20 tons and grows to a
length of 40 feet.
• In Texas it is illegal to have sex with a fish, in Florida it is illegal to get a fish drunk. (13)
1. Fins – modified limbs, used for movement
2. Gills – the things with which fish breathe, instead of with lungs
3. Ectothermic – fish derive their heat from the environment
4. Poikilothermic – fish conform to the heat of the environment
5. Ichthyology – study of fish
6. Viviparous – giving birth to their offspring
7. Anemone – poisonous plant that lives at the sea bottom and eats fish, clown fish lives
8. Bony fish – found in lakes, rivers, seas (Lungfish, Trout, Bass, Salmon, Perch, Parrot
9. Cartilaginous fish – large marine animals (sharks)
10. School – group of fish
Kingdom: Animalia Phylum: Chordata → Vertebrata
Closest relatives: Gnathostomes (fish) 1.1
o Tetrapods (with exception of Caecilians) - developed 4 limbs that allow movement on
o Skin is included in respiration: thin, smooth, with mucous glands 
o Ectothermic – unable to regulate body heat 
o Amphibians: “dual life” on land and in water
Infant stage (larval/juvenile stage) passes in water
Adult stage passes on land, in moist habitats 
o Eyelids (to keep eyes moist) 
o Tongue (as a sensatory organ and a way to catch prey) 
o Larger brain and more developed nervous system 
o A closed double-loop circulatory system 
o A three-chambered heart (mixed blood) 
Small lung capacity → moist skin also part of respiration system (and osmotic balance)
Some adult forms develop a lung for permanent gas exchange ; in others it is carried
completely by the skin and the oral cavity 
o Life cycle characterized by metamorphosis
o After the hatching of the eggs, the first stage is the larvae (for frogs: tadpole) 
Grills; fishlike tail (enables movement) ; feeds on plankton 
o During metamorphosis develops legs, lungs, external eardrums, digestive system,
loses its drills and tail  and the place of the eyes changes 
o In adult age crawls on land (sometimes returns to water for mating, egg laying) 
o Laying and fertilization of eggs is held in water or damp environment 
o External fertilization: male stimulates female to lay eggs and fertilizes them in the
same time 
o High egg mortality due to the lack of a protective shell and thus, inability to adapt to
environmental changes 
o Sticky tongue catches prey; thin maxillary teeth break it down
o The food’s path: esophagus→ stomach→ small intestine→fluids digest→ large
intestine → cloacal vent 
o help maintain the balance in nature by eating insects [6
o production of biomedicines 
o Bioindicators – physically respond to chemical changes in the environment (e.g.
sterilization) ; can also act as weather forecasts 
Some salamanders and frogs have tongues 10 times bigger than their actual size 
1. Dyeing dart frog/ Dendrobates tinctorius 
(Order Anura; Neobatrachia; Family Dendrobatidae)
Range: Guyana, French Guinea, Brazil, Suriname
Diet: insects, spiders, worms, slugs
Life style and cycle changes: Eggs hatch into tadpoles, which
with time grow legs, absorb their tails, lose their gills
and eventually start breathing air through lungs and
jumping with their back legs, turning into frogs 
In variety of colors http://de.academic.ru/dic.nsf/dewiki/179102
Length reaches 50 mm (the biggest f the Poison Dart Frogs )
3. Marble Salamander/ Ambystoma opacum 
(Order Caudata; Family Ambystomatidae)
Habitat: damp woodlands, forests, ponds, streams
Range: Eastern USA
Diet: all are carnivores and eat snails, worms, slugs, insects
Attracted by smell and movement 
Life style and cycle changes:
Live underground, except in night and during breeding period
Lay eggs (50-150) in holes, where water can reach them.
Then the eggs hatch (usually autumn/winter)
Grow quickly; takes 2 to 6 months to reach mature age
3. Boulengerula taitana
(Family Caecilidae; Order Apoda/Gymnophiona/Caecilians)
Habitat: moist highlands, plantations, gardens 
Range: Taita Hills, Southeastern Kenya 
Diet: ants, worms, termites, earth insects
During juvenile stage, eat mother’s skin 
Life cycle: 2-9 eggs hatched in underground chambers 
2 years needed to reach adult form; colorize 
Burrowing amphibians: dig holes and live
underground, in loose soil or leave liter ; 
Amphibian – dual life in water and on land
Bioindicator – indicator of changes in the environment
Burrowing amphibians – amphibians that generally dig underground tunnels where
Carnivore – an animal that eats meat
Ectothermic – unable to regulate body temperature; cold-blooded
External fertilization – fertilization occurs in the environment, not in the body
Larvae – the young, “water” stage of amphibians
Metamorphosis – the process of transformation of the amphibian from larvae to adult
Mucous glands – glands that produce liquid to keep skin moist
Tadpole – the larvae stage of the frog
Tetrapod – and animal that has four limbs
How does this phylum fit into the evolutionary tree?
- Kingdom - Animalia
Class – Reptilia
The name Reptilia comes from the Latin repere meaning “to creep”
There are four orders that come from the Reptilia class and they are:
1)Crocodilia (crocodiles and alligators)
2)Sphenodontia – includes only 2 species – tuatara from New Zealand
3)Squamata ( worm and cold blooded lizards, snakes)
4)Testudines ( turtles and tortoises)
Does this group have symmetry? – They all have bilateral symmetry
Other closely related groups are:
- Class Amphibians
- Class Aves ( birds)
How long ago did humans share a common ancestor with this group?
-The earliest known reptile was the Hylonomus around 300millions of years ago that
developed from amphibians and is the precursor of mammals ( people)
1. Reptiles belong to the Reptilian clade of the cladogram. They are cold blooded, lay
amniotic*, tough-shelled eggs, and are covered by scales or scutes*. They are
2. Reptiles are known to both lay eggs (oviparous*) and deliver live babies.
Egg Layers: Turtles, Crocodilians
Livebearers: Some Lizards, Some Snakes:
Examples: Boas, Vipers
3. Lizards use their limbs to aid their bodies in sliding on the ground, because they are too
weak to permanently lift up their bodies. Snakes can move in three different ways:
lateral undulating, straight crawling, and side winding.
4. Reptiles resort to camouflage to avoid predators- many have patterns on their scales to
resemble the environment they are in. Others resort to playing dead, in hopes that the
predator won't notice them. Others become extremely rigid, which is called tonic
immobility. Many other lizards resort to changing their diets according to the predators
that they face. they choose less mobile and easier pray, in contrast to fast and agile bugs,
for example. Examples: ....
Anaconda Eunectes murinus
-from the order Squamata
-biggest snake on the planet
-Habitat: South America – lives in the jungle around water(rivers, lakes)
- not venomous, have teeth, but don’t bite, slow - moving
-rely on their strength to strangle and swallow their pray
- Food: usually fish and other aquatic creatures; rarely caimans, other snakes and even jaguars
- lay eggs
Gavial - Gavialis gangeticus
-Order – Crocodilia;
- size 7 m
- famous with its long stout and precious skin
-Habitat: Asia – India , Nepal around water – Indus and Ganges mostly
-Ecology – it is under great danger of disappearing as a specie because people kill it for its
- Food: fish, insects, small mammals, birds
-breed in November and then the female lays about 40 eggs
Tuatara – Sphenodon punctatus
- One of the two only survivors of the order Sphenodontia; the others died 60 million
years ago and that;s why it’s called living fossil
- Remained the same as it was 225 million years ago
- Once lived in New Zealand, but they were killed by rats and people
- Now are found on small islands around New Zealand
- Lay eggs, then they reach maturity when they are 15-20 years old
- Can live more than 100 years
- Food: insects, lizards, seabird eggs
Vocab words and terms to know:
1)scale – platelike dermal or epidermal structures common for fishes and retiles
2)Amniotes – group of tetrapod vertebraes that include mammals, reptiles and birds
3)oviparous – that produce eggs
4)colon – last part of digestion for reptiles
5)fetus – a developing vertebrae after the embryonic stage
6)Age of Reptiles ( MEsosoic era) – reptiles (dinasours) started developing a lot and inhabited
the whole planet
7)secondary palate – anatomical structure that devides the nasal and oral cavity and enables
animals to continue breathing after they submerged under water
8)scute(scutum) – bony plate or scale as of the shell of a turtle
9) crypsis – the ability not to be seen ,camouflage
10)tonic immobility – the ability to become rigid in order to defend and hide
Elena, Ell, Elisa 10/2
• The scientific name for mammals is mammalia.
• Mammals have bilateral symmetry
It is a type of symmetry seen in animals having an elongated body shape. The body parts are
arranged on either side of an imaginary axis. Such an animal can be cut into two equal halves
by only one plane passing through the axis. In such animals the body axis is described as
median-longitudinal or antero-posterior axis. In general, triploblastic animals are bilaterally
symmetrical. All higher animals from flat worms to vertebrates exhibit bilateral symmetry.
• Living group of mammals is most closely related to primates, which include
monkeys, apes, and lemurs.
Comparative maps suggest that rates of chromosomal change in mammals can vary from one
to ten rearrangements per million years 1–4. On the basis of these rates we would expect 84 to
600 conserved segments in a chicken in comparison with human or mouse.
- Hair is a defining characteristic of mammals, no other organisms possess true hair and
all mammals have hair covering at least part of their body at some time during their
life. An individual hair consists of a rod of cells that are reinforced by a protein known
as keratin. Hair grows from skin cells called follicles. Hair can take on several
different forms including fur, whiskers, spines, or horns. Hair serves numerous
functions. It can provide insulation, protect the skin, serve as camouflage, and provide
- Mammary glands, like hair, are a uniquely mammalian trait. Though present in both
males and females, mammary glands only fully develop in females. Mammary glands
consist of ducts and glandular tissues that secrete milk through nipples. Young
mammals obtain milk from their mother by feeding from her nipples. The milk
provides the young with much needed protein, sugars, fat, vitamins, and salts.
- The three middle ear bones in mammals are the malleus, incus, and stapes. These
bones—commonly referred to as the hammer, anvil, and stirrup—are unique to
mammals, no other animal group has them. The middle ear bones transmit sound
vibrations from the tympanic membrane or eardrum to the inner ear and transforms
them into neural impulses. The malleus and incus are derived bones that were once
part of the lower jaw in mammal ancestors.
- Mammals all have one single bone comprising their lower jaw. In all other animals,
more than one bone comprises the jaw.
• How do they reproduce?
All mammals reproduce sexually, which produces offspring that are unique because they have
a mixture of genes from both parents.
1. Monotreme Reproduction
Monotremes such as the duck-billed platypus and the echidna lay young inside of eggs. The
eggs are similar to birds or reptile eggs except that the monotreme eggs are much softer. The
young hatch after a few days and continue to grow as the mother nurses them. Echidnas nurse
their young in a pouch on the underside of their belly and the platypus nurse young in an
underground nest. Monotremes don’t have teats and secrete milk onto their fur for the young
to lap up.
2. Marsupial Reproduction
Marsupials give birth to live, tiny underdeveloped offspring that continue their development
inside the mother’s pouch. Once outside the birth canal, the offspring make their way through
the mother’s fur to find her nipples, which are often inside the pouch.
3. Placental Mammal Reproduction
Placental mammals (eutherians) have prolonged gestation in which the embryo remains in the
uterus to develop fully, receiving nourishment from the mother via the placenta. Length of
gestation varies depending on the mammal. Some gestation times of mammals include:
* Mice: 21 days
* Rabbits: 30-36 days
* Dogs & cats: 60 days
* Cattle: 280 days
* Bats: 4-5 months
* Elephants: 22 months
Generally, the larger the mammals, the longer the gestation period, however, there are
exceptions to this rule.
Generally, the larger the mammal, the lower the number of young in a litter. While small
rodents produce several offspring in a litter every season, large mammals, like the elephant,
may only have 4 calves over its entire life of around 50 years.
• What is their life cycle? (eggs, larvae, juvenile, adult, etc)
Mammals life cycles can vary, especially in some varieties of mammals that may not be so obvious,
such as dolphins and platypuses. The life cycle, while seemingly simple, can be fairly complicated and
cause for many questions. There are some commonalities in every mammal's life cycle and also some
exceptions to the rules.
1. All mammal life cycles start with mating. A male and female copulate, many times after a mating
ritual, dance or call, and the cycle of life begins. Mating in mammals takes place inside of the female's
body. The male inserts the male sex organ into an opening in the female and the mating process
2. Meiosis is a term defining what happens post-mating. The two cells, or gametes, combine. Male
gametes are sperm and female gametes are eggs. Most often, male gametes have flagella, similar to a
tail, which helps the male reproductive cells travel to the female gamete. This all occurs within the
female's body. This, much like the hard outer shell of a bird egg, is what protects the "precious
cargo"---a new life. This new life is known at this point as the zygote, or the combined egg and sperm.
3. Gestation periods are the point from when the zygote is formed until the baby is developed
birthed. In humans, this period is an average of nine months. During gestation, the cells are constantly
multiplying. The cells, known as stem cells, form into different parts of the body and each stem cell
has a special purpose in development.
4. Females give birth to the infants, which come in different numbers ranging from one to several,
depending on the species. For example, except in rare occurrences when the cells split or fertility
drugs are used, female humans give birth to one child. In the instance with cats, they can have litters
ranging from two to six kittens. Also, birthing patterns are different. Female humans give birth to
babies head first, as a way for the baby to be able to breath as soon as possible after the water has
broken. In dolphins, babies are born tail first, so that they have ample time to surface to breath after
5. Mammals do not go through stages of larvae, nymph or anything of the like. Mammals simply
grow into larger versions of themselves at birth, until they are at an adult age and growth stopping
point of maturity. Once reaching maturity, female cycles (or periods) begin and males begin seeking
out females for courtship and possible mating. This is where the life cycle starts over again.
• How do they obtain food? How is it digested?
• Oral cavity- sensation of food in the oral cavity sends a reflex that activates the
salivary glands that deliver saliva through ducts to the oral cavity
• Pharynx- in the throat which intersects the windpipe and the esophagus. When
people swallow, the top of the trachea (windpipe) is closed off by the
cartilaginous flap, called the epiglottis.
• Esophagus- The esophagus moves food from the pharynx down to the stomach
• Stomach- secretes gastric juice and all of the bacteria are killed. Also located
in the gastric juice is pepsin, which is an enzyme that hydrolyzes proteins. The
pepsin only breaks the peptide bonds adjacent to specific amino acids.
• Small intestine- digestion takes place
• Large intestine- reabsorbs water that has entered the alimentary canal. The
final phase of the digestive system is when the feces reach the terminal part of
the colon called the rectum. This is where the feces are stored until they are