are a series of interconnected canals run back from the head to the upper lobe of the tail in a distinct line.Infraorbital canal
on the head extends from behind the eye along the snout.Supraorbital canal
from above the eye to the snout and connecting with the infraorbital.Supratemporal canal
leads back over the top of the head.
These canals open to the outside skin through tiny pores which allow water in.How it works:-
water displaced by the movement of fish in the area - this creates small waves which pass over the hairs inside the canals - they then send signals to the sharks brain. The sharks own movement also creates waves which bounce off the fish and return to the shark creating a vibration echo map
. In this way the shark can detect its prey.
Sharks can also detect temperature change as they have a row of pores
around the pectoral fins and gills - called pit organsElectroreception:
The lateral line pores around the snout have modified to respond to fluctations in the electrical fields in the sharks habitat. These sensory organs are calles ampullae of Lorenzini
- small gel-filled sacs which have sensory nerve at the base of each pore which transmits the electrical signals put out by the prey to the brain. Actively hunting sharks can have as many as 1500 ampullae around the snout whilst sedentary ones might only have a few hundred. The ampullae are so sensitive thest they can pick up voltage fluctations of just over 10 millionths of a volt!
It appears that when sharks are close to their prey that the electrical sense takes over from sight or smell.Taste:
- is another chemosensory function similar to smell. Gustatory sensory cells
are found in small pits lining the mouth and throat - dissolved chemicals from the bitten object attach to these cells which send a signal to the brain. This determines whether the shark will eat or reject the meal.Hearing
:- ears are completely internal embedded within the frontal skull and responsible for balance and equilibrium. The inner ear consists of a series of ducts and sacs filled with endolymph
. Simply put
:- the endolymph fluid moves about and sways as the shark banks and this swaying registers on sensory hair cells which send signals to the brain resulting in a sense of imbalance that the shark then corrects.So to summarise the sensory organs of sharks/rays are:-
Chemoreception - smell & taste
Photoreception - visual
Mechanoreception - touch
Electroreception - electric fieldsPHEW......end of Q1 and Q2 TO BE CONTINUED