Page 83 - Fish and Amphibians (Britannica Illustrated Science Library)

78 AMPHIBIANS FISH AND AMPHIBIANS 79

Newts Anatomy of a Newt

Newts, unlike salamanders, have no grooves along their sides. Adults
long with salamanders, newts are the most primitive of terrestrial FRONT FEET have elongated bodies 3-4 inches (8-10 cm) long, with well-developed
vertebrates. Of the three main surviving groups of primitive Newts have four tails. They have four limbs, with four toes on each front foot and four or five
toes on each of on each hind foot. Another peculiarity is that they have teeth in both upper
A amphibians, newts most closely resemble the animals from which their front feet. and lower jaws. Their heads and eyes are relatively small. Smell is their most
all amphibians are descended. Some of their habits are also more important sense for finding food and for social interaction.
complex and varied. Most of the time they live on land, but during the
mating season they return to the water. Unlike frogs and toads, newts TAIL
Newts keep
and salamanders keep their tails as adults. They are found in temperate their tails as
regions of the Northern Hemisphere. PALMATE NEWT adults.
TRITURUS HELVETICUS
3.5 inches (9 cm)
long, with a pale belly
Courtship and Reproduction Feeding
NEWTS
Like salamanders, these tiny animals are
Courtship and mating involve a showy exhibition by both male and
usually active at night. The smallest newts
female. The male must find a female of the same species and bring
her a packet of sperm, which he deposits on the ground or in a pool. feed on small invertebrates, whereas larger
Fertilization is internal, and the female gathers the packet into her cloaca. newts can eat fish, amphibians, and eggs.
Habitat Northern Hemisphere
Number of species 360
1 DANCE Order Urodela
Males are attracted by
the female's belly,
swollen with eggs. The
males draw her
attention with their
showy pigmentation and Newt Species
the flexible crest along
Amphibians are divided into three
their back and tail. HIND FEET
groups, distinguished by their tails The hind feet are
2 EXHIBITION and legs. Newts and salamanders have BELLY webbed in males
The male swims in front tails and belong to the order Urodela. but not in females.
of the female, displaying Some produce toxic substances for A white or pale
his nuptial attire. He defense from predators. They are very belly is one of the
raises the toothed crest small; the largest newt may reach 6 inches distinctive traits
on his back and slaps (15 cm) in length. of this species. NEWTS AND WATER
GREAT CRESTED NEWT
his tail while producing Triturus cristatus As semiaquatic creatures, newts
secretions from his spends from three to five Male's return to the water during mating
months of the year in the water. crest
cloacal glands. season. They are found in North
America, Europe, all of continental
Asia, and Japan. Adapted to
3 CONNECTION various habitats, they climb trees
The male deposits his and dig in the ground in addition
packet of sperm and to living in the water.
then gently guides the
female toward it,
pushing her with his side.
The female gathers the
packet into her cloaca.
Males have a crest,
and females have
only a yellow stripe
along their backs.
EASTERN DEFENSE
NEWT Some newts are highly
Notophthalmus
viridescens dangerous because they
4 EGG LAYING The larvae go release a toxic substance
Egg After the eggs are through a when attacked. One such
fertilized, the female special juvenile
stage called the species is the California
finds a place to “red phase.” newt. It can be
deposit them, recognized by its bright MARBLED NEWT SMOOTH NEWT
attaching them to Triturus marmoratus
coloring, which serves as Triturus vulgaris
underwater spends its whole life in the One of the most
a warning to predators. water, both as a juvenile and
vegetation or rocks. as an adult. colorful