12.2 Flashcards
The majority of the avian body is covered with
Feathers
The majority of the avian body is covered with
Feathers
performs many of the functions for which hairy skin is responsible in mammals, including:
avian feather coat
∙ Where feathers are present, the ____ is relatively thin.
Skin
consists of an epidermis and dermis (corium) underlain by the subcutis(hypodermis)
Feather skin
is homologous with that of mammals, differences are apparent in the layers of the dermis
epidermis
a superficial layer
stratum superficiale
a deep layer
stratum profundum
During incubation, many bird species develop a median ventrosternal
brood patch.
brood patch.
Feathers
such as ducks and geese, do not develop brood patches. Instead, they warm their eggs with plucked down feathers
waterfowl
is thicker in featherless regions, corresponding with the mechanical forces to which these parts of the body are subjected.
stratum corneum of the epidermis
(keratinized epidermis) is particularly hard at the edges of the beak, in the scales and spur, and on the dorsum of the claws
horn
is found at the cere, between the scales and on the plantar surface of the claws ∙
Soft horn
∙ Birds do not have
sweat glands.
is secreted by the glandulae venti located on the labia of the cloaca
mucoid substance
are found in only three locations:
o above the tail: the uropygial gland o in the external acoustic meatus: the auricular glands
o in the cloaca: the vent glands
Sebaceous glands
present consistently in chickens and water
birds, but may be absent in psittacids and
pigeons;
Uropygial gland
The oily holocrine secretory product is used
in preening to cover the feathers in a fatty
waterproof film.
Uropygial gland
It is thought to also play a role in the
storage of Vitamin D, allowing this nutrient to be taken up by the beak during grooming
Uropygial gland
are observed on the head and neck of birds
cutaneous structures
typical features of chickens, are variably developed in different breeds
comb, wattles and earlobes,
of this species presents as a bulge of skin that may become engorged when the bird is aroused
wattle
of this species presents as a bulge of skin that may become engorged when the bird is aroused
muscovy duck
can reach considerable proportions in sexually aroused male turkeys
snood
is also covered in numerous wart-like cutaneous caruncles that extend to the neck and breast
head of turkeys
a beard comprising a tuft of hard, dark bristles is present on the neck
fully grown turkey
of the guinea fowl consists of a cone-shaped peg of bone overlain by rough skin with a strongly keratinized epidermis.
crest (helmet)
The flexor surfaces of the joints of the wings (alae) are spanned by membranous folds of skin referred to as
Patagia
Only at the shoulder joint are these skin folds present on both the flexor and extensor surfaces of the limb
Patagia
at the transition from the neck to the wing
Patagium cervicale
between the shoulder and carpus
Propatagium
− between the alula and digit 2
Patagium alulae
extending from the breast to the elbow
Metapatagium
− between the elbow and the manus
Postpatagium
The interdigital space between the second, third and fourth pedal digits is spanned by short folds of skin known as
interdigital webs
these are used for swimming and extend to the tips of the toes
interdigital webs
possess an additional web between digits 1 and 2
Pelecaniformes
such as the coot, lack interdigital webbing, possessing instead small flaps of skin that extend from the side of the second to fourth toes
Rails (rallidae)
, which extends over the rostral portions of the maxilla and mandible. Its dermal layer is tightly attached to the periosteum. There is no subcutis.
Rhamphotheca
takes the place of the lips and teeth of mammals.
beak
In newly hatched chicks, a cone-shaped _____ is present on the rostral portion of the upper beak; Used by the chick to break open the egg shell during hatching, the egg tooth is subsequently shed
egg tooth
In some species, the skin at the base of the upper beak is variably thickened and is referred to as the
cere(cera)
∙ The featherless skin of the tarsometatarsus and digits (podotheca) is covered in
scales
(scale) On the dorsum these are relatively large
scuta
(scale)while those found on the plantar
surface are smaller and typically hexagonal in shape
scutella
The joints of the pedal digits are underlain
pads
These include the_________ which bears weight when the foot is placed on the ground,
metatarsal pad
that conform closely to the underlying surface during perching
digital pads
are located at the tips of the digits of the foot
claws (ungues)
forms a cone-shaped covering of the underlying bone. It consists of a dorsal plate and a plantar plate.
claws
are adapted for scratching and are thus shorter and relatively straight.
claws
are an occasional atavistic finding in domestic chickens and geese
Claws on the wings (ungues digiti manus)
Located on the caudomedial tarsometatarsus where, in males, it is mounted on a large pyramidal bony protuberance
spur
∙ It grows approximately 1cm per year, up to a total of around 6cm, and can thus be used in estimating age.
spur
Related phylogenetically to the scales of reptiles, these are the distinguishing feature of all birds
feathers
confer upon birds the capacity for flight
feathers
are located on the antebrachium, manus
and the alula. Their number is consistent within species. Around 10–20
secondary remiges arise from the forearm, while ten primary remiges
originate from the manus. Up to four alular remiges are present. Each
remex has accompanying coverts. There are no remiges in the brachial
region, which is covered with coverts.
Remiges
are characterised by a slightly curved shaft and
asymmetrical vexillae.
Remiges
Arising from the rump, it form the basis of the tail.
Their shaft is usually straight.
Near the centre of the tail, the vexillae are generally symmetrical.
Towards the periphery, there is an increasing tendency towards
asymmetry of the vexillae (the medial vexillum becoming narrowed)
and curvature of the shaft.
Rectrices (sing. rectrix)
consist only of a calamus with a
large tuft of keratinised filaments
at its tip
Down Feathers/Plumules
Definitive (adult) down feathers
are particularly numerous in water
birds.
Down Feathers/Plumules
Hardly any down feathers are
found on chickens, their
function being taken over in this
species by
Semiplumes
s are similar to down
feathers, but have a clearly
defined rachis. Their association
with an afterfeather, including an
aftershaft, indicates that
semiplumes are actually a
modified form of covert.
Semiplumes
Like down feathers, their role is to
provide thermal insulation.
Semiplumes
are
specialised down feathers
that continually produce a
powdery substance consisting of
minute (approximately 1µm)
keratin granules.
Powder Down Feathers
They are especially plentiful in
pigeons.
powder down feathers
It is presumed that the powder
acts as a waterproof coating for
the plumage
powder down feathers
are down-like feathers
that lie immediately adjacent to
the follicle of contour feathers. The
follicles of filoplumes are rich in
free nerve endings and Herbst
bodies are found in the surrounding tissue
Filoplumes
are located on the head.
They line the base of the beak and
form the eyelashes.
Bristles have a rigid shaft with few
barbs and are associated with
numerous mechanoreceptors
bristle
is very unique and in most species is
specially adapted for flight. It is a very lightweight and
delicate yet very strong
Avian skeleton
the sternum flying species have a pronounced ____ the
place on the sternum that the flight muscles attach to
keel
is a
large bone situated
between the mandible
and the temporal
bone. It allow the
upper beak to be
opened wherever the
mandible is depressed
quadrate bone
No parietal bone with
one more turbinate
bone.
quadrate bone
Upper jaw is movable, swings upward and downward
(articulates in the brain case by nasal-frontal hinge)
kinetic
is movable, swings upward and downward
(articulates in the brain case by nasal-frontal hinge)
upper jaw
Have a large orbits separated by
interorbital
do not extend caudal to the
nasal-frontal hinge
Holorhinal
centers ossify to surround and protect the
ear
otic
Dentary (largest bone) forms the mandibular symphysis
distally
lower jaw
forms the mandibular symphysis
distally
Dentary (largest bone)
Lumbar and Sacral are typically fused
synsacrum
is the last
vertebra where feathers are attached
Pygostyle
exhibiting a large ventrally directed keel “carina” w/c serve
as bony surface for the flight muscle (pectorals and
supracoracoideus)
sternum
cranial most point of sternum
Carinal process
- 3 pairs of bones which supports the
wings
Formed by:
fused clavicles or Furcula, it connect to carinal process of sternum
Coracoid – most robust, hollow (clavicular air sacs)
Scapula
pectoral girdle
– largest in the
wing bone
humerus
Have pneumatic foramen at
proximal end w/c allow the
invasion of clavicular air sacs
humerus
forearm
radius and ulna
fused distal row of carpals
and metacarpals
carpometacarpus
– represented by a small
projection of radial side of the
CMC
allular
fused at their
distal extremities and enclose a
large enterosseus space between
them
major and minor
is the
largest and contains 2
phalanges
major digit
– fusion
of 3 bones. Illum,
ischium and pubis
pelvic girdle
is
present between ilium and
ischium
illiochiatic foramen
have nutrient foramen
Femur (thigh bone)
is a very
prominent trochanter lateral to
its head
Proximal end
r possesses a
large groove (rotular groove);
also have two condyles which
articulate with the tibiotarsus
and fibula
distal end of femur
largest of the leg
bone
tibiotarsus
Fusion of tibia and the proximal
row of tarsal bones
tibiotarsus
Fusion of central tarsal,
distal row of tarsals and the
metatarsals II-IV
tarsometatarsus
The metatarsus carries ? digits
4
Only the first digit
extends in a plantar direction
anisodactyl
Both the first and fourth digits
assume a plantar orientation
Zygodactyly
are generally symmetrical.
Towards the periphery, there is an increasing tendency towards
asymmetry of the vexillae (the medial vexillum becoming
vexillae
for example, coverts make up the fan of the peacock, the sickle feathers of the rooster and the crest of the cockatoo
ornament feahters
are distributed over the body in species-specific tracts (pterylae). ∙
coverts
are not only anchored to the skin, but are also attached by syndesmoses to the underlying bones
calami
usually consist of a distal pennaceous portion (pars pennata) and a proximal plumaceous portion (pars plumacea)
vexillae
most robust, hollow (clavicular air sacs)
Scapula
coracoid