Slide 1 : ELECTROLOCATION
Slide 2 : A pulse-type electric fish is the Elephant Nose Catfish.
It sends out spurts of electricity less than a millisecond in length.
Larger eels (over 1 m in length) can produce charges of 450 to 650 volts of electricity.
Active electro-location : Active electro-location Electroreceptors are used to detect a slight change of electric field caused by nearby objects.
Electric fishes can thus electrically 'see' objects in an environment where vision is useless (at night, or in murky water).
This process is called 'active electro-location' because the source of electricity that they use for electro-location is their own electric organ.
This is similar to the “sonar” technique used by submarines to detect nearby objects by the speed at which sounds are bounced back.
Lateral line organs : Lateral line organs Other fish use weaker electric fields to navigate murky waters or to monitor their surroundings.
For instance, bony fish and some frogs have a lateral line, a row of sensory pores in the skin, that enables them to detect electrical current in water.
Some can detect the L-serine (a chemical found in the skin of mammals) diluted to 1 part per billion.
Slide 6 : MAGNETIC SENSES
Magnetic Sense : Magnetic Sense Together, the flow of molten material in the earth's core and the flow of ions in the atmosphere generate a magnetic field that surrounds the earth.
Amazingly, a number of animals are able to sense this magnetic field.
Magnetic sensing : Magnetic sensing Sensory perception inaccessible to humans.
Variety of living organisms have the ability to perceive magnetic fields
Can use information from the earth's magnetic field in orientation behavior.
What is Cryptochrome ? : What is Cryptochrome ? A compass helps us navigate by detecting magnetic north
Animals with magnetic sense are able to identify direction and navigate long distances through
Cryptochrome is a signaling protein found in a wide variety of plants and animals.
Animals with Magnetic sense : Animals with Magnetic sense Salmon, Oncorhynchus nerka
Sea turtle, Dermochelys coriacea
Spotted Newt, Notophthalmus viridescens,
Lobsters, Panulirus argus,
Honey bees, Apis mellifera, and
Fruitflies, Drosophila melongaster can all perceive and utilize geomagnetic field information.
What is Magnetite ? : What is Magnetite ? Each of these animals has deposits of magnetite in their nervous systems.
Magnetite=small magnet-like crystals
Align themselves with magnetic fields
Act like microscopic compass needles.
These crystals may be the key to revealing how animals sense magnetic fields.
Slide 12 : SPECIAIZED SENSES
IN
ANIMAL WORLD
Slide 13 : INSECTS
What are Pheromones ? : What are Pheromones ? Chemical signals
Triggers a natural response in another member of the same species.
Types
Alarm pheromones
Food trail pheromones
Sex pheromones
Pheromones : Pheromones German Biochemis Adolf Butenandt
Obtained a chemically pure pheromone and named it "bombykol" for the silkworm moth, "Bombyx mori" from which it was extracted.
It signaled, "come to me!" from great distances.
"It has been soberly calculated that if a single female moth were to release all the bombykol in her sac in a single spray, all at once, she could theoretically attract a trillion males in the instant,"
ANTS : ANTS Can detect small movement through 5 cm of earth.
Can see polarized light.
Bees : Bees Have chemoreceptors (taste receptors) on their jaws, forelimbs and antennae.
Worker honey bees have a ring of iron oxide "magnetite” in their abdomens that may be used to detect magnetic fields.
They may use this ability to detect changes in the earth's magnetic field and use it for navigation.
Slide 18 : Can see polarized light
Can see light between wavelengths 300 nm and 650 nm.
Worker honey bees have 5,500 lenses "ommatidia” in each eye.
Mosquitoes : Mosquitoes Johnston organs Attracted to host by human body odor (especially foot odor), carbon dioxide, body heat and body humidity.
Song of Cicada : Song of Cicada Male cicadas have loud noisemakers called –Timbals on the sides of the abdomen base.
Their "singing" is not the stridulation (where two structures are rubbed against one another) of many other familiar sound-producing insects like crickets
Timbals are regions of the exoskeleton that are modified to form a complex membrane with thin, membranous portions and thickened "ribs".
Slide 21 : Contracting the internal timbal muscles produces a clicking sound as the timbals buckle inwards.
As these muscles relax, the timbals return to their original position producing another click.
The interior of the male abdomen is substantially hollow to amplify the resonance of the sound.
Slide 22 : A cicada rapidly vibrates these membranes, and enlarged chambers derived from the tracheae make its body serve as a resonance chamber, greatly amplifying the sound.
They modulate their noise by wiggling their abdomens toward and away from the tree that they are on.
Additionally, each species has its own distinctive song.
Noisiest Insects : Noisiest Insects Some cicadas produce sounds up to 120dB
Slide 24 : SPECIAL SENSE
of
MOLLUSC
Osphradium : Osphradium Olfactory organ in certain gastropods
=respiratory organ.
The main function of this is to test incoming water for silt.
LOWER ANIMAL CPU : LOWER ANIMAL CPU Both invertebrate and vertebrate animals can have complex brains.
Of the invertebrates, squid an octopuses have the most developed brains, in part to process information coming from their highly sophisticated eyes.
A medium sized octopus will have a brain containing over 100 million neurons, and can show learning behavior.
Still, this is far away form mammalian brains that contain on the order of 10 billion neurons.
Giant squid : Eye is 11 inches in diameter.
Largest animal eye on Earth.
Retina can contain up to 1 billion photoreceptors Giant squid
Slide 28 : SPECIAL SENSE
of
FISHES
Drum fish : Drum fish Collects underwater sound vibrations with an air bladder.
The signals are then sent from the air bladder to the "weberian apparatus" in the middle ear and then to the inner ear.
Hair cells in the inner ear respond to the vibration and transmit sound information to the fish brain.
Deep sea fish : Deep sea fish Only have rods in the retina: 25 million rods/sq. mm.
Perhaps they need this high density of photoreceptors to detect the dim biolumninescence that exists in the ocean depths.
Four eyed ..Anableps : Four eyed ..Anableps Can see in air and water simultaneously.
Each eye is divided by flaps, so there is one opening in the air and one in the water
Shark : Shark Electrosensing receptors with thresholds as low as 0.005 uV/cm.
Receptors may be used to locate prey.
The dogfish can detect a flounder that is buried under the sand and emitting 4 uAmp of current.
Slide 33 : Some sharks can detect fish extracts as concentrations lower than one part in 10 billion.
Some sharks sense light directly through the skull by the pineal body.
The thresher shark has an eye up to 5 inches (12.5 cm) in diameter.
Slide 34 : Catfish have 3 or 4 pairs of whiskers, called barbels, to find food.
Also has 100,000 taste buds.
Slide 35 : REPTILIAN
SENSE
Chameleon : Chameleon The eyes can move independently.
Therefore, it can see in two different directions at the same time.
But when the chameleon spots something to eat, both eyes focus on the target.
Slide 37 : Focus at one spot gives the chameleon the stereoscopic vision it needs to judge distance before it strikes with its sticky tongue.
Slide 38 : AVIAN
SPECIAL SENSE The pictures projected on this free session
belong to the beholder s on the internet.
We thank them
OWLS : OWLS Nocturnal animals have large eyes, with a wider pupil, larger lens and increased retinal surface collect more light.
Cannot move their eyes within the orbit.
Extraordinary rotational ability in the neck (through 270°)
Some animals of the night have acquired a spherical lens and widened cornea to compensate for reduced eye movement.
This combined with a wide cornea increases the animals field of view allowing the head and eyes to remain motionless.
Falcon : Falcon Can see a 10 cm. object from a distance of 1.5 km.
Visual acuity is 2.6 times better than human.
Can see sharp images even when diving at 100 miles/hr.
Hawk : Hawk Normal vision for people is 20/20.
A hawk's vision is equivalent to 20/5.
This means that the hawk can see from 20 feet what most people can see from 5 feet.
Eagle : Eagle Eyeball length = 35 mm (human eyeball length = 24 mm)
Visual acuity is 2.0 to 3.6 times better (depending on the type of eagel) than that of humans.
Predatory birds ...Eagle : Retina has 1 million photoreceptors per sq. mm.
Can see small rodents from a height of 15,000 ft
Have two to three yellow spots in retina Predatory birds ...Eagle
Penguins : Penguins Has a flat cornea that allows for clear vision underwater.
Penguins can also see into the ultraviolet range of the electromagnetic spectrum.
A penguin's eyes are adapted to see clearly both in air and under water.
Penguins have color vision and are sensitive to violet, blue, and green wavelengths of light.
They have moderate hearing but can recognize their own young ones in crowd.
Slide 45 : Mommy!!
I could hear you in crowd…
Pigeons : Pigeons With eyes mounted laterally on their heads, pigeons can view 340 degrees...everywhere except in back of their heads.
Can detect sounds as low as 0.1 Hz
Slide 47 : MAMMALIAN
SPECIAL SENSE This presentation is brought to you by ….. Bisbio.in
Elephants : Elephants Have hearing range between 1 and 20,000 Hz. The very low frequency sounds are in the "infrasound" range.
Humans cannot hear sounds in the infrasound range
Cat Senses : Cat Senses Has hearing range between 100 and 60,000 Hz.
Olfactory membrane about 14 sq. cm.
For comparison, humans have an olfactory membrane of about 4 sq. cm
Dog senses : Dog senses Olfactory membrane up to 150 sq. cm.
Can hear sound as high as 40,000 Hz
Slide 51 : Thank you
Dr. S. Biswas
for your best sense
Hit at … http://bisbio.in orCall 09814016083, 09855516083 oremail … bisbioin@gmail.com or amanbiswas60@gmail.com : Hit at … http://bisbio.in orCall 09814016083, 09855516083 oremail … bisbioin@gmail.com or amanbiswas60@gmail.com For all your
Biology Problems
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Slide 53 : THE END