Nervous System
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Largest single part of the nervous system
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Great white shark’s brain
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Y shaped
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60 centimeters long
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- brain consists of different regions
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Hind-brain
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Midbrain
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Forebrain
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Ventricles are filled with cerebrospinal fluid, helps chemical regulation of the brain
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Sharks sense of smell takes up â…” of the brain
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Brain receives and processes messages such as hunger, sleep, and electromagnetic pulses.
Five main structures:
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Telencephalon
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Diencephalon
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Mesencephalon
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Cerebellum
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medulla
Telencephalon
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Located in the forebrain, accounts for 33% of the brain
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Receives olfactory information
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Responsible for integration of memory, learning and awareness
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Receives sensory input from the diencephalon
Diencephalon
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Accounts for 6% of the brain
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Controls motivation, production of hormones and relay information to the endocrine system
Mesencephalon
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Accounts for 14% of the brain
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Receives input from the retina
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Responses for behavioral processes to stimuli
Medulla
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Accounts for 24% of the brain
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Sharks homeostasis
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Acts as a relay station between brain and spinal cord
Cerebellum
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Accounts for 18% of the brain
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Motor tasks
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Target tracking and analysis
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The hindbrain consists of the brainstem
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The brainstem bristles the posterior cranial nerves
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Responsible for conveying input from the ear and electrosensory systems
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Sharks have a highly developed nervous system and sensory systems
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Use their nervous system to find prey
Adapted these senses to their own environment
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Four main senses:
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Chemoreception (smell and taste)
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Mechanoreception (touch and hearing)
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Photoreception (vision)
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Electroreception ( sense electrical fields)
Chemoreception
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nostril leads to the olfactory bulb in the brain
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Smells is the most important sense - - -> â…• of the brain is used to analyze smell
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Allows them to find food sources from long distances
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Sharks might become aggressive when hunting
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Stimulated by fish blood more than humans
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Mechanoreception
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Sound and movement are detected by two sensory organs: ears and lateral line
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Vibrations of sound ripple through the water along the ear canal to the inner ear
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Hearing is related to the lateral line. Lateral line is a series of fluid filled canals that are beneath the skin that goes to the head down the body
Lateral line is sensitive to low frequency vibrations
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It allows for the shark to detect direction and movement around them
Photoreception
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Have 3 eyelids for protection
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upper/lower eyelid protect the eye
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The 3rd eyelid is a moveable eyelid.
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When a shark is feeding, the membrane covers the eye for protection. This makes the shark temporarily blind.
Electroreception
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Sharks are able to detect electrical impulses that are generated by the nervous system
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Sensing devices are clusters of tiny pores in the skin around the head
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Ampullae of lorenzini are small sensory organs that are filled with conductive jelly
