The document details the integument system, outlining the structure and functions of skin and its derivatives, including the epidermis and dermis. The epidermis serves as a protective layer, while the dermis contains connective tissue crucial for body heat regulation and defense against injury.

1. STUDY GUIDE FOR INTEGUMENT AND ITS DERIVATIVES IN PHYLUM CHORDATA
(ZOO100 BARRIGA)

2. HOOVES OF HORSES
Understanding the parts of the hoof, being able to label the right parts and understand their functioning is essential in order to understand what makes up
“healthy” hooves. The hoof is an extremely complex structure and the single biggest factor affecting the horse’s soundness.
The central role of a hoof is to act as a shock absorber and protector of the internal structures. The hoof withstands huge forces from the weight of the horse
– whilst standing still and in motion – hence the adage ‘no hoof, no horse’. The outer wall of the hoof is divided into three sections: the toe, quarter and heel.
Heel bulbs: soft horn tissue with a cushion of connective tissue on the interior side, providing the bulbs with springiness and flexibility. The bulb’s corium
produces a delicate, pliable horn, and this horn contains a large amount of water and sweat glands.
Heel buttress: the “platform” on which the hoof lands. Without a solid landing platform, the rest of the hoof cannot function properly and can be damaged
irreversibly. The heel buttress extends into the foot to form a solid ‘buttress’.
Frog: forms a “V” into the centre of the sole and is a major functioning part of hoof health. The frog is the shock absorber as well as the energy dissipator of
the hoof. It is dynamic and changes in response to terrain, diet, and other hoof demands.
Central sulcus of the frog: a small indent, about the size of a thumb. There should be no cracks showing infection and/or contracted heels. This can
predispose the horse to lameness if not addressed correctly.
Apex of the frog: the tip of the frog. The portion closest to the apex should be substantial enough to touch the ground when the horse is bearing weight.
Hoof wall: the part of the hoof which is visible when the horse is standing. It covers the front and sides of the coffin bone. The wall comprises the toe (front),
quarters (sides) and heel (back). The hoof wall should be smooth, a bit shiny, and free of prominent rings.
White line: is a white-yellowish line around the inside of the hoof wall that connects the wall of the hoof capsule to the inner foot. This area should be solid
with no separation, so that dirt, mud and environmental insults are not allowed into the foot.
Bar: provides traction and support for the back of the hoof, preventing the hoof from over-expanding during landing, as well as acting as “skid brakes”. The
bars should never be “dug out” but “skimmed” down to sole level.
Collateral groove: should range between 1,6 – 3,2 cm (2/3 – 1 1/4 in) deep from apex to heel, and should be clean and free of thrush. Under the apex, the
collateral groove should be about 10-15 mm deep (2/3 in) as the coffin bone sits just on top of the apex at about 1,2 cm (1/2 in) in the foot. A collateral
groove shallower than this could be a sign of thin soles, which is going to cause the foot to be inadequately protected from environmental abuses.
Seat of corn (also known as corns): a corn is a bruise that forms between the sensitive and insensitive layers of the sole of the foot. The ‘seat of corn’ is the
most commonly affected area. It is located between the hoof bar and wall, near the heel.

3. Toe & point of breakover: The toe helps protect the inner foot and the circumflex artery that runs around the edge of the coffin bone. The toe should be
short enough that the breakover during the hoof lifting off the ground is quick and does not “drag” on the toe. This area, covering about 2,5 cm (1 in) from
the tip of the toe towards the apex, is known as the toe callus.
Coronary band: the junction between the hair-producing skin of your horse’s lower limb and the hoof wall. The outermost layer of skin on the coronary band
is a lifelong cellular proliferating zone, meaning that it’s always producing new cells. As these keratinocytes undergo maturation and eventual death, they
form the middle of the horn of the wall. This constant adding of cells in the coronary segment causes the middle layer to move downward to reach the ground
– this means your horse’s hooves grow by 6-8 mm every month on average.
Periople: responsible for producing the outer shiny layer of the hoof wall. This outer layer prevents moisture loss from the inner layer of the hoof wall. It also
stops moisture from going into the inner layer.
Growth rings: externally visible ridges in the hoof wall that show differences in the rate and quality of growth of the hoof wall. Growth rings can show
problems within the hoof capsule, or simply be an external map of changes in nutrition, activity, or a systemic disturbance that has altered the hoof growth
at some point in time.
References:
https://www.mylifeisbetterwithhorses.com/everything-you-need-to-know-
aboutkeeping-your-horses-hooves-healthy/
THE ANATOMY OF A HORN
Horns are made of three layers; the outside of the horn is made of hard keratin, the same material that fingernails are made of. Just under the keratin layer
is a blood supply that connects the horn to the skull of the goat. The inside of the horn is called the core which is also connected to the skull. This is why
after the horn has broken through the skin, the dehorning process becomes more complicated.

4. References:
https://www.ironoakfarm.net/should-i-dehorn-or-disbud-my-goat/
BIRDS INTEGUMENT
Generally the legs feet and claws are structured to allow a bird to take off land
climb and grasp with them.

5. Since birds spend most of their lives perching the feet and legs are covered with tougher skin than the skin on the rest of the birds body. Like the shape of
the bill the anatomy of birds feet tells us much about the ecology of different species of birds. Some of the lower bones of the foot are fused to form the
tarsometatarsus a third segment of the leg specific to birds.

6. The functions of bird skin are the same as for other vertebrates – to keep out pathogens and other potentially harmful substances, retain vital fluids and
gases, and serve as a sensory organ. The continual renewal of the skin acts to repel parasitic microorganisms. The skin of birds also produces and supports
feathers. With feathers, the skin also plays an important role in thermoregulation. Although largely covered by feathers, the integument is unfeathered on
the beak, feet, and, in some species, other areas.
References: https://boundbobskryptis.blogspot.com/2017/11/bird-feet-anatomy.html
https://avesbiology.com/avian_integument.htm
HUMAN NAIL MATRIX
Your nail matrix is where your fingernails and toenails form. Your nail matrix has two parts: the germinal matrix and the sterile matrix. Your nail matrix
creates new cells that become your fingernails or toenails. About 90% of your nail growth comes from your germinal matrix. Your sterile matrix is
Avian skin consists of two layers, the epidermis and dermis. The outer
layer, the epidermis, is generally very thin and pliable. The dermis is
thicker than the epidermis and contains blood vessels, fat deposits,
nerves and free nerve endings, several types of neuroreceptors, and
smooth muscles that move the feathers (Lucas and Stettenheim1972).

7. responsible for the remaining 10% of cells that make up your fingernails and toenails, but is more important in keeping your nail attached to the underlying
skin.
Your nail matrix is made of special cells whose main job is to make new fingernails or toenails. Each nail matrix produces 196 layers of cells that combine to
make each of your fingernails and toenails. Each nail matrix is constantly making new nail cells, unlike your hair follicles, which go through periods of rest.
SNAKE SKIN
Even dead snakes are capable of biting - they may react to touch and other stimuli for
many hours after they have been killed. Be careful!
Dorsal scales
The dorsal scales cover the snake's back. These are the scales you can see when the snake
is 'sitting' on the ground. You count these scales at the widest part of the snake's body.
This is the mid-body region, about halfway down the snake's length.
The diagram on the right shows you how to count these scales. In this particular example,
our snake has 17 rows of dorsal scales at mid-body. This is often just abbreviated as '17
midbodies'.

8. Australian pythons, colubrids and elapids have an odd number of
midbody scale rows. Blind snakes have an even number of midbodies.
Australian colubrid and elapid snakes usually have between 13 and 23
midbody scales. Australian pythons have between 31 and 70 midbodies.
Ventral surface
There are a few characteristics of the snake underside that may be useful
in identification. These are:
Ventral scales
These are the 'belly scales' of the snake. They run from the neck down to
the bum. Pythons have ventral scales that are about half the width of the
body. Both colubrid and elapid snakes have ventral scales that are about
the same width as the body.
Anal scale
This is the scale just in front of the cloaca (the snake's 'bum'). The anal
scale may be single or divided.
Subcaudal scales
These are the scales underneath the snake's tail. Scales are either single
or divided, but snakes may have a combination of both single and divided
subcaudal scales.

9. RABBIT SKIN (HAIR)
The bodies of all vertebrates are invested by an outer protective covering, the integument or skin, which is partly responsible for retaining the body shape.
The skin is comparatively thick and covered with hairs. It consists of two main layers; the epidermis which is ectodermal in origin and the dermis which is
mesodermal in origin. Several other structures which are derived from the skin are found associated with it, e.g., hairs, claws, nails, various glands, etc.
The hair base is only living, while the cells of hair become horny and die beyond the skin. The
hair is made only by the secretion of seba ceous gland opening into the hair follicle. With each hair
follicle is attached a small smooth muscle, the erecter pili , for erecting the hair due to fear,
excessive cold, etc.
References:
https://www.notesonzoology.com/rabbit/external-morphology/external-morphology-of-rabbit-with-
diagram-chordata-zoology/7642

10. FISH SKIN
The fish have fins and a spine and most of them have scales and breathe through their gills. As for their fins they are appendices that they use to
maintain their position, move, direct or stop.
There may be individual fins located along the body of each species, such as the dorsal fin (back), caudal fin (tail) and anal fin, as well as paired fins such
as the pectoral fins (breast) and the pelvic fins (hip)
Fishes like catfish have a fleshy lobe behind the dorsal fin, called adipose fin. The dorsal and anal fins mainly help the fish not to roll on their sides. The tail
fin primarily meets propulsion functions so that the fish can move forward. The paired fins help with steering, stopping and floating. Scales on most bony
fish (most freshwater fish other than ganoid-sized fish, and catfish that do not have scales) are ctenoid or cycloid .The first ones have irregular edges that
have small projections called Ctenii on their posterior edge. The cycloid scales have smooth rounded edges. The bass and most other spined fish have
ctenoid scales. The bass and most other fish with spines have ctenoid scales. Most fish also have a very important mucus layer that covers their body which
helps them prevent infections.
In many freshwater fish, the fins are supported by rigid spines that are usually quite sharp playing a defensive role. The dorsal and caudal fins are
constituted by rays, which are less rigid and frequently branched.
References:
https://ourmarinespecies.com/c-fishes/the-anatomy-of-fish/

11. THE SKIN | Functional Morphology of the
Integumentary System in Fishes
Individual fish scales showing some morphological features of
major scale types.
(a) Placoid scale (odontode) from the ventral body of a spiny
dogfish shark, Squalus acanthias (b) Ganoid scale of a
longnose gar ( Lepisosteus osseus ) shown as a transparency.
(c) Elasmoid scale (cycloid type) of a teleost fish. (d) Elasmoid
scale (ctenoid type) of a teleost fish. (e) Scute (bony plate) of a
teleost, the armored catfish Corydoras aeneus .
Reference:
THE SKIN | Functional Morphology of the Integumentary
System in Fishes - Scientific Figure on ResearchGate.

12. TORTOISE ANATOMY AND DESIGN
Tortoises’ spines are attached to their shell, which is composed of carapace (the top portion) and plastron (the bottom portion).
The piece of scute directly behind the
head is known as the nuchal. Then
all the scutes directly behind the
nuchal are known as
vertebrals/centrals.
Radiating along the sides of the shell
are scutes called marginals. Named of
course because they are at the
margins or fringes of the shell.
The first pair of scutes directly behind the
head are known as the gulars.
These are then followed by the
humerals, then the pectorals, followed
by the abdominals and femorals. Note
how these scutes are basically named
after the part of the body they are
The final and most rearward scutes
would be, of course, the anals.
Together these pieces make up the shell, one of the most amazing pieces of defensive
located at or near.
machinery ever evolved.
References:
619872ff029a
https://reptilis.net/chelonia/bodyplan.html

13. https://medium.com/@moderntortoise/basic-tortoise-anatomy-design-
MAMMARY GLAND IN HUMAN
In monotremes, nipples and teats are absent and breasts do not form. Milk
is released from ducts into the flattened milk patch or aerola on the surface
of the skin (Fig. 1.14 a). The point of infant's snout is shaped to fit the
surface, permitting vigorous sucking. At sexual maturity adipose tissue
builds up under the mammary glands to produce breast from which milk is
released. In common language, this is termed let down.