Page 13 - Shark

Nasal brain power
sac Some sharks have brains that are similar Jaw-opening muscle
in weight to those of birds and mammals, when pulls jaws forward
compared to their overall body weight. The nasal so teeth protrude
Forebrain
sac, or sensory part of the nose, is close to the Cartilage support of gill
front part of the brain. arch, forming a hoop
Midbrain around the gullet
Gill arch, with gill
filaments, where
Hindbrain Ovary (eggs visible respiration takes
within its wall). place
When ripe, eggs
Brain of a pass into a tube for Nostril
lemon shark fertilization

Tongue is rigid, supported
by a pad of cartilage

Jaw-closing muscle

Cartilage in floor of gullet Open
gill slits
(below)
Aorta,
with branchial
arteries

Heart
blooD circulation
Blood from the body
collects in the first chamber
of the shark’s heart, then is Shut
pumped through the second gill slits
and third, while the fourth (below)
prevents blood from
Cartilage flowing back into the
at base of heart. The aorta and branchial
pectoral fin arteries circulate blood to the gills,
where each branchial artery divides
into tiny blood vessels in the gill
Cartilage of filaments. As sea water passes over
pectoral girdle the gills, oxygen is picked up and
supports pectoral fins carbon dioxide released.
and protects heart

Gall First open, shut
bladder fooD processor dorsal To breathe, water comes in through the shark’s
Food begins its digestion process in the fin mouth, passes over the gills, and out the gill
shark’s stomach, then passes into the slits. A nurse shark pumps water across its
Pectoral intestine, where the multilayered scroll valve Stomach’s gills, by closing its mouth and contracting
fin increases the area for absorbing digested descending the mouth and gullet walls. When the
food. A greeny-yellowy fluid, stored in the gall limb mouth opens, the gill slits shut, when
bladder, is released into the gut, where it helps the mouth closes, the gill slits open.
fats be absorbed. The shark’s large liver also
aids digestion, processing fats, carbohydrates,
and proteins.
Second
dorsal
fin

Anal fin
Pancreas,
Pelvic Stomach’s Spleen, producing
Rear view of whole body fin ascending producing red enzymes to help
of shark, showing gullet limb blood cells digest food in gut

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