External Structures of Dog Fish Shark

Ms. Hays – Spring 2014

External Nares (Nostrils) Pair of openings on each

side of the head cranial from the eyes

Taken up into the smaller of the two openings and expelled through the larger openings

Water passes a sensory membrane allowing the shark to detect chemicals in water

Spiracles Small openings caudal

behind the eyes Provides oxygenated

blood directly to the eye and brain through a separate blood vessel

Spiracles

Nostrils

Mouth Location: front of the

head Function: to eat; used for

the intake of water that passes through the gills

Gill Slits 5 vertical slits Location: in front of the

pectoral fin Function: to take the

oxygen from the water passing over the gills and discharge carbon dioxide

What is the function of the gill slits in this picture?

Gas Exchange!

Lateral Line Location: extends

noticeably from the pectoral fin past the pelvic fin.

Function: senses tiny pressure disturbances in the water

The lateral line is a line of pores that run along each side of the shark that help the shark orient to movement & sound.

Cloaca Location: between the

pelvic fins & claspers Function: Opening for the

sex organs as well as being used for excretory waste

Clasper Only present in males! Location: down the

middle of each pelvic fin Function: Used to

introduce the sperm into the cloaca of the female

What is the name of the structure that is on the side

of the pelvic fins that is only present in males?

Claspers

Fins 5 fins:

1st & 2nd Dorsal Fin – anti-roll stabilizing fins Pectoral Fin – steering fins Pelvic Fin – stabilizing fins Caudal Fin – provides thrust

What are the names of the 5 fins of a shark?

1st Dorsal Fin2nd Dorsal FinPectoral FinPelvic FinCaudal Fin

RostrumPointed snout located at the front of the head

Dorsal Spines Used defensively by the

shark Each has a poison gland

associated with it

What is a characteristic of the lateral lines and what

is a characteristic of dorsal spines?

Lateral Lines: senses tiny pressure disturbances in water

Dorsal Spines: used as a defensive mechanism, each has a poison gland associated with it

Denticles Tooth-like scales on the

surface of the sharks skin Reduce drag and allow

sharks to swim more silently & smoothly.

What is one characteristic of the dermal denticles on the surface of the sharks

skin?Tooth-likeUsed to allow sharks to swim more silently &

smoothly

Ampullae of Lorenzini Small vesicles and pores

that form part of an extensive sensory network system.

Found on the head of the shark

Detect weak magnetic fields produced by other fishes

This enables the shark to locate prey that are buried in the sand or to orient to nearby movement

They may also allow sharks to detect changes in water temperature

Where are the Ampullae of Lorenzini located on the

shark?Head

Nictitating Membrane A membrane that is

present over the eyes that covers & protects the eyes during feeding.