Page 45 - Fish and Amphibians (Britannica Illustrated Science Library)

40 DIVERSITY FISH AND AMPHIBIANS 41

Long and Flexible GILLS Reproduction

Seahorses breathe
through gills. 35 The male has an incubating pouch in which the
he seahorse is a small ocean fish that belongs to the same family as pipefish and sea species female deposits her eggs. The sac closes, and
the embryos develop, nourished by the male. He
dragons (Syngnathidae). Its name comes from its horselike head. In fact, no other fish later expels the young, now mature and
of seahorses live in the independent, through a series of contractions.
T genus has its head at a right angle to the rest of its body. Because it cannot use speed Caribbean, the Pacific Ocean,
to escape from its predators, the seahorse has the ability to change color to blend in with its and the Indian Ocean.
environment. The reproduction process of these fish is also very unique. The male has an
incubating pouch in which the female deposits the fertilized eggs.

BLACK-STRIPED PIPEFISH PECTORAL FIN
Syngnathus abaster One on each side,
EYES for lateral
One of the slowest fish in the sea, the Large, for movement
acute vision
black-striped pipefish moves by means
of slight undulations of its pectoral Movement
fins, which can vibrate up to 35
times per second. The body of a seahorse is crammed into an
armor of large, rectangular bony plates. NOSE
Pipe-shaped,
They swim very differently than other fish. giving the During the mating season the female lays
Adopting an upright position, they use their some 200 eggs in the male's pouch using her
dorsal fin for propulsion. They do not have head a 1 egg-depositing organ. There the eggs are
an anal fin, but rather a long tail that rolls horselike 0.4 fertilized. When the time for birth arrives,
into a spiral. They use it to hold onto shape the male clings to seaweed with his tail.
underwater plants.
Classification inch
HEAD
Thirty-two species of seahorse have been identified (1 cm)
worldwide. Classifying them is at times complicated
because individuals of the same species can change color The size of a
and develop long filaments of skin. The size of adult seahorse at birth
seahorses varies enormously, from the tiny Hippocampus
minotaur—a species discovered in Australia that never TRUNK
grows beyond 0.7 inch (1.8 cm) long—to the enormous The body is
Hippocampus ingens, a species in the Pacific that reaches supported
by the spinal
over 12 inches (30 cm) long. It has no pelvic or caudal fins, BONY PLATES
column.
but it does have a tiny anal fin. UNROLLED Its body is covered
The tail with concentric rings
ROLLED UP straightens out of bone.
The tail rolls up
WEEDY SEA DRAGON into a curl. by unrolling.
Phyllopteryx taeniolatus
Its shape is typical of this family, The male bends his body backward and
GRASPING TAIL
although its tail is not suitable for forward, as if having contractions. The sac's
With their long 2 opening widens, and the birthing process
grasping, like those of seahorses are, tails, seahorses can begins. Soon the young begin to appear.
and it has a more elongated profile. cling to plants on TAIL DORSAL FIN
Seahorses swim
Its body is covered with seaweed. the seafloor. Can be upright, propelled by
extended to a their dorsal fin.
fully vertical
position

SEAWEED
The fish lets it stick
to its body so that
it can escape
detection.
Camouflage LINED SEAHORSE
Hippocampus
Since they cannot use speed to escape erectus
from predators, seahorses and dragon
fish use camouflage as a defense
strategy. They change color to blend in As the male's belly contracts, the young
with their environment, grow skin 3 seahorses are gradually born. Each one is
filaments shaped like seaweed, and use Habitat Caribbean, Indo-Pacific Ocean 0.4 inch (1 cm) long. They begin to feed
their heads to climb along the seaweed Number of species 35 on phytoplankton right away. The
in which they live, swinging from one birthing process can last two days, after
plant to another. Size 7-12 inches (18-30 cm) which the male is exhausted.