Page 47 - Fish and Amphibians (Britannica Illustrated Science Library)

42 DIVERSITY FISH AND AMPHIBIANS 43

Elegant Contours Electric
organ
Pectoral fin
Tail
Spiracle
he Rajiformes are an order of cartilaginous fish related to sharks;
THERE ARE Gill arch
they have the same skeletal structure, the same number and type
ABOUT
T of fins, and similarly shaped gill slits. Rajiformes are distinct in that BLUE-SPOTTED
RIBBONTAIL RAY Muscle
their gill slits are on the underside of the body, which is flat with pectoral Taeniura lymma 300
fins joined to the trunk in the shape of a disk. The body is usually
covered with denticles, and many have a row of dorsal spikes. They SPECIES OF Electric
have a variety of colors, with spots and blotches. They often burrow Habitat Indian and Pacific oceans RAJIFORMES Ray
Diet Crustaceans
into the mud of warm seas. Electric rays (Torpedo sp.) are highly
Length Up to 6.6 feet (2 m) active fish with electric organs on each
RAYS Head Poisonous Yes side of the head. Each electric organ is
Raja sp.
made of numerous disk-shaped cells,
connected in parallel. When all the cells fire
at once, an electric current is discharged into
the water at 220 volts, enough to stun the prey.
Flying Through
PELVIC FINS
the Water POISONOUS TAIL BLUE LINES Small in size
has a dangerous run along the whole TAIL WITH
Unlike most fish, rays have weak, slender tails stinger. length of the tail. EYES ELECTRIC CHARGE
that do little to power their swimming. They Turned outward
move with their enormous pectoral fins, which are
joined to the head and have a characteristic rhomboid
shape. Their movement rises and falls in an S curve,
as if they were flying underwater.

PECTORAL
FINS
ROUGH RAY are joined to the
Raja radula body just behind the PECTORAL FINS
head near the gills. Joined to the head

TAIL
is slender and lacks
the strength for
swimming.

Blue-spotted
12.4 miles Ribbontail Ray
per hour Its body is covered with blue spots. It
inhabits reefs, caves, and crevices. Its
(20 km/h) tail has a powerful stinger that
injects venom into predators Nasal Mouth
when it feels threatened.
Row of teeth orifices
Smiling Face
The ray's face is unique. It is
protected by a flap on the
underside of its body. Its hornlike
mouth is adapted for grasping
crustaceans, and the five gill COMPARED
slits on each side are for Nasal orifices FOR SIZE Sawfish
breathing underwater.
The manta ray is the Fish of the order Pristiformes have long bodies with an
Hornlike mouth
largest in the world. In unmistakable face, adorned with 32 pairs of denticles on
spite of its large size, it is 23 feet (7 m) 8.2 feet (2.5 m) 3.3 feet (1 m) each side. The females give birth to 15 to 20 young,
FINS HEAD
LITTLE SKATE move up and down remains upright, harmless, feeding only on MANTA Weight 3,300 BUTTERFLY THORNBACK which are born with a protective membrane over their
Raja erinacea Gill arch during swimming. looking forward. sea plankton. RAY pounds (1,500 kg) RAY RAY teeth to keep from hurting the mother.