comparative study of sense organs in fish, amphibian, reptile, aves, mammal.

1. INDIRA GANDHI NATIONAL TRIBAL UNIVERSITY AMARKANTAK
Department of ZOOLOGY
Sensory Organs in higher vertebrates
2019

2. What are Sensory Organs?
Sense organs are the specialized organs
composed of sensory neurons, which help us to
perceive and respond to our surroundings. There
are five sense organs – eyes, ears, nose, tongue,
and skin

3. External senses
Taste Gustatoreceptors
Sight Photoreceptors
Smell Olfactoreceptors
Touch Tangoreceptors
Heat Thermoreceptors
Cold Caloreceptors
Pain Frigidoreceptors
Hearing Phonoreceptors
Pressure Mechanoreceptor

4. Internal Senses
1.in EYES
2. in EARS
3.in Brain

5. An Eye
The main sensory organ of the visual system
is the eye, which takes in the physical stimuli
of light rays and transduces them into
electrical and chemical signals that can be
interpreted by the brain to construct
physical images.

6. Fish eyes are similar to the eyes of terrestrial
vertebrates like birds and mammals, but have
a more spherical lens. ... Fish retinas generally
have both rod cells and cone cells (for
scotopic and photopic vision), and most
species have colour vision. Some fish can see
ultraviolet and some are sensitive to polarized
light.
Eyes of Fishes

7. Fish Eyes

8. Amphibians have eyes which are adjusted to
seeing both on land and in water.
Amphibians are unique in that they are
capable of extra-ocular vision - sensing light
energy using structures other than the eyes.
For example, amphibian skin acts as a sense
organ which often replaces the need for
vision.
Eyes of Amphibians

9. Amphibian Eye

10. Reptiles active at night tend to have
smaller eyes than those active during the
day. The pupils of nocturnal species tend
to be relatively large. This improves the
reptile’s ability to gather light but reduces
their visual acuity. Many nocturnal species
have slit-shaped pupils. Species active
during the day tend to have round pupils.
Eyes of Reptiles

11. Reptilian Eye

12. Eyesight is a bird's most critical sense and
the one it relies on the most for flight,
evading predators, and finding food. ... They
have much denser rods and cones, the
"seeing" cells, packed on the retina, giving
them superior vision in both black-and-
white and color.
Eyes Of Birds

13. The Avian Eye

14. Eyes Of Mammals
(Marsupials and
Placental mammals)
• No bone or cartilage in sclera
• No skeletal muscle
• No photomechanical movement
• Dichromatic Vision
• No fovea
• Most have blood vessles within
the ratina
• Accomodation limited by passive
action of lens capsule on lens.

16. Ears
ear is a delicate organ located in the temporal
region of the skull. It is called membranous
labyrinth, which evolved in primitive
vertebrates for maintenance of balance and
posture. Hearing function of this organ
evolved for the first time in anurans when
they started living in terrestrial environment,
where sound waves travel faster and to longer
distances.

17. Ears of Fishes
fishes have developed sensory mechanisms
for detecting, localizing, and interpreting
sounds. Two independent but related
sensory systems used by fish to detect
sound are the inner ear(the auditory
system) and, to a lesser extent, the
mechanosensory lateral line system, which
is generally used to detect vibration and
water flow.

18. Fish Ear

19. As sense organs for hearing, the papillae,
which appear for the first time in
amphibians, have cells like those in lower
vertebrates that serve the same purpose.
There are two types of papillae: the
amphibian papilla, which is found in all
amphibians, and the basilar papilla, which
is found in some amphibians.
Ears of Amphibians

20. Frog ear
Ambhibian ear

21. The reptile's senses of sight, smell, and
hearing are similar to those of other
vertebrates, though the levels of
development of these senses vary
among reptile groups. Snakes lack ears
and can detect only ground vibrations
or airborne vibrations of low frequency.
Ears of Reptiles

23. Birds hear a smaller frequency range than humans, but
they have much more acute sound recognition skills.
Birds are especially sensitive to pitch, tone, and rhythm
changes and use those variations to recognize other
individual birds, even in a noisy flock. Birds also use
different sounds, songs, and calls in different
situations. Recognizing the different noises is essential
to determine if a call is warning of a predator,
advertising a territorial claim, or offering to share food.
Many birders study those calls and birding by ear can
be useful for not only identifying birds but also
understanding their behavior.
Ears of Birds

24. Avian Ear

25. Mammals possess the best developed hearing power among all
Vertebrates. Langena elongates to form a spirally coiled cochlea. In middle
ear cavity instead of one bone mammals have 3 ear ossicles namely incus
mallus stapes.Which transmit sound vibrationsfrom tymphanic membrane
to the fenestra ovalis that leads to scala vestibuli of cochlea.Mammals als
have various size of ear pinna to collect sound wavesand diret them tothe
auditory canal.Cloecha is a specialized and highly sensitive organ of
hearing. Its cross section reveals three long chembers scala media and
scalatympani the middle chamber is filled withendolymphwhile the other
two are filled with perilymph.The organ of corti is attached to the bassilar
membrane and carries sensory hair cells and supporting cells and the
cochlear nerve at the base A tectorialmembrane floats in the
Ears of Mammals

26. middle of scala mediaand touches the
hairs of sensory cells when vibrates by the
sound vibration resulting in the generation
of a nerve impulse tha travels via cochlear
nerve to the brain

27. A sensory system consists of sensory
neurons (including the sensory receptor
cells), neural pathways, and parts of the
brain involved in sensory perception.
Commonly recognized sensory systems
are those for vision, hearing, touch, taste,
smell, and balance.
Brain

29. Brain of Fishes
Fish typically have quite small brains relative
to body size compared with other
vertebrates, typically one-fifteenth the brain
mass of a similarly sized bird or mammal.[6]
However, some fish have relatively large
brains, most notably mormyrids and sharks,
which have brains about as massive relative
to body weight as birds and marsupials.

30. The general structure and functional organization of the
amphibian brain includes several apparently primitive
features (such as a small size and relatively little cell
migration and areal differentiation, these being less severe
in anurans than in other amphibians) as well as the
standard major brain areas and basic connectional patterns
found in all vertebrates. Evolutionary specializations are also
apparent, especially in anurans where expanded visual and
auditory midbrain areas are present. The forebrain contains
many of the basic vertebrate systems and general
organization of connections, but the functional organization
of sensory systems is quite different from the familiar
pattern seen in mammals, birds and reptiles.
Brain of Amphibians

31. The diversity of reptiles and their evolutionary relationship to
mammals make reptilian brains great models to explore
questions related to the structural and functional evolution of
vertebrate neural circuits. To this end, comparative studies
seek to identify homologies — structural or molecular
similarities that are due to common ancestry — at a variety of
levels, for example, brain regions, circuits or cell types.
Homologies can be inferred from extant species by using a
comparative approach within a phylogenetic framework.
Vertebrate brains have been classically compared in terms of
morphology, connectivity, and neurochemistry; however,
adult neuroanatomy may not be sufficient to determine
homologies without ambiguity.
Brain of Reptiles

32. Brain of Birds
Bird brain is characterized by enormous enlargement of
cerebral hemisphere optic lobes and cerebellum. cerebral
hemisphere become enlarges owing to enlargement of
corpus straitum which is called hyperstraiatum but pallium is
thin and surface has onliy white matter. Olfactory lobes are
highly reduced attatched to the anterior end of the cerebral
hemisphere. optic lobes are enormous as birds need good
control over muscles and tendons which comes from trilobed
highly enlarges cerebellum is called vermis as it has
transverse folds and the lateral lobes are called floculi. Birds
brain is instinctive brain that can carry out complex but
sterotype fucntion such as nest building. spiral cord still has
equal control over the body.

33. Urodele brain is primitive nd reflects their
sluggish nature and underdeveloped
sense organs. Olfactory lobes, optic lobes,
and cerebellum are reduced and cerebral
hemisphere are also small and smooth.
pineal and parietal bodies are present but
reduced. there is no saccus vacculosus
and corpus straitum is weak.
Urodele Brain

34. The most obvious difference between the
brains of mammals and other vertebrates is in
terms of size. On average, a mammal has a
brain roughly twice as large as that of a bird of
the same body size, and ten times as large as
that of a reptile of the same body size
Brain of Mammals

35. Size, however, is not the only difference: there are also
substantial differences in shape. The hindbrain and
midbrain of mammals are generally similar to those of
other vertebrates, but dramatic differences appear in the
forebrain,which is greatly enlarged and also altered in
structure. The cerebral cortex is the part of the brain that
most strongly distinguishes mammals. In non-mammalian
vertebrates, the surface of the cerebrum is lined with a
comparatively simple three-layered structure called the
pallium. In mammals, the pallium evolves into a complex
six-layered structure called neocortex or isocortex.Several
areas at the edge of the neocortex, including the
hippocampus and amygdala, are also much more
extensively developed in mammals than in other
vertebrates.

36. References