AMPHIBIANS IN HERCULES
Introduction
Amphibians:
from “amphi” (double) “bios” (life). Most have an aquatic
larval
stage and transform into a semi-aquatic adult. Have been on earth
over
300 million years. Probably first vertebrates to spend part of their
lives
on land. Very adaptable, live in many varied habitats including the
desert
and the subarctic. Can tolerate cold but must have moisture
(desiccation
= death). Desert species estivate during periods of extreme
heat.
Most have lungs at adult stage but oxygen and carbon dioxide are
also
exchanged through the skin. Cannot change their color, but can
change
their shade which aids in camouflage.
Characteristics
Naked
skin (no fur, feathers, or scales). Skin contains many glands,
some
produce defensive toxins (see
No
claws on toes. Ectothermic: body temperature fluctuates with that
of
the surrounding environment. Animals must move from place to
place
to regulate their body temperature.
Reproduction
Most species return to some
water source to breed and lay eggs. Larval
stages have gills and may
exploit different food sources than adults.
Rates of development vary from
species to species, some a matter
of weeks, others may take a
year or longer. Lungless salamanders
such as slender salamander
reproduce on land in moist woodlands
or stream-banks. Development
is direct with no larval stage.
The
Conservation
There
is great concern among scientists about a worldwide decline in
amphibian
populations. Some sites have reported a 50 to 90 percent
drop
in numbers. Western species have been particularly hard hit. As
amphibians
are an important part of many wildlife food chains
continued
declines could have far-reaching consequences.
Classification
Animals found here are divided
into two orders:
Salientia (Anura), the tailless frogs and toads;
and Caudata (Urodela)
the salamanders.
Newts are a type of
salamander.
FROGS AND TOADS
Adult
frogs and toads are tailless. Frogs have smoother skin and larger
hindlimbs
adapted for swimming and leaping. Toad skin is thicker, drier,
with
distinctive warts. Most species have a well developed ear (tympanum)
and use
their voices to defend territory, attract mates, and signal distress.
All of
the local species return to some body of water to breed. Fertilization
is
external. Male fertilizes eggs released into the water by the female as he
clasps her (amplexus). Fertilized eggs hatch into tadpoles which develop into
froglets and toadlets.
Pacific Chorus Frog (Pseudacris regilla )
Size: Small (3/4 -
2"), climbing frogs. Toes have
wide, sticky tips with an
extra joint for flexibility. Various colors of grey,
green brown, and tan.
Can darken or
lighten color but does not change from one color to another.
Distinctive black
eye stripe. Call is a very loud “Kreck-ek”.
Habitat: Found in
marshes, ditches, ponds and streams in grassland or
wooded
areas. Common in backyard gardens. Nocturnal and diurnal.
Common
throughout most of the year except during exceptionally dry
or
cold periods.
Reproduction: Eggs are
attached to vegetation in shallow water during
January
to July breeding season. Males arrive at breeding site first where
their
calls attract females.
Food: Adults eat insects,
spiders, isopods, and snails. Tadpoles eat
vegetation
and small aquatic life, and are in turn food for a variety of
animals.
Red-legged Frog (Rana
aurora dray tonii )
Size: 2 - 5".
Brown to reddish color on back with dark flecks and
blotches.
Red on belly and underside of legs. Dark mask bordered
by
pale jawstripe. Well-defined ridges (dorso-lateral folds) extend
from
behind the eye down the length of the back. Hind toes are
webbed.
Males are smaller than females.
Habitat: prefers sheltered aquatic areas but also found in damp
woodlands.
During winters it stays in mud at the bottom of ponds and streams
until
breeding season. Nocturnal and diurnal, also very shy. Weak guttural,
stuttering call is most commonly heard during the breeding season.
Reproduction: Irregular, grape like egg masses up to 10" across
are
attached to vegetation in shallow water during short (1-2 week)
breeding
season from January to May.
Food: Insects, isopods and possibly other small amphibians.
This frog
is
a favorite prey of the endangered
species
are declining in the Bay Area.
Now
listed as threatened on the Federal Endangered Species list.
Western Toad(Bufo boreas)
Size: 2 1/2 - 5". Stout, short legged and warty. White
or cream colored
mid-dorsal
stripe. Dusky colors of gray, brown, or green above with
warts
surrounded by dark blotches. Stripe may be weak or absent in
juveniles
who also may have bright yellow patches under their feet.
Oval
paratoid glands behind eyes. Males in breeding condition develop
dark
nuptial pads of slightly roughened skin on the inside of one or
more
fingers. Males have a weak chirping voice because they have
no
vocal sac. Females are voiceless.
Habitat: Variety of
habitats including gardens, grasslands, woodland
meadows,
ponds , springs, and slow moving streams. Nocturnal in
warm
areas, diurnal at higher elevations. Their thick warty skin allows
them
a more terrestrial existence than frogs although they will retreat
to
rodent burrows if the temperature rises. Unlike frogs, who can leap
out
of danger, toads will rely first on camouflage. If this fails the toad
will
face the predator head on. A bite on the toad’s head will release the
irritating
toxin stored in it’s paratoid glands into the predator’s mouth.
The
bad taste and subsequent nausea discourage most from taking a
second
bite. Toads can be very long-lived, with captive specimens
surviving
20 years or more.
Reproduction: Jelly- like
strings of eggs (up to 16,000 per female) laid
in
shallow water during breeding season from January to July.
Food: Insects of all kinds, crayfish, sowbugs, snails,
slugs, and
occasionally
other toads.
Salamanders are lizard-like in
body shape but lack scales or claws and have soft, moist skin.
Slow moving.
Most species are terrestrial, spending all but the breeding season seeking out
the protection of rodent burrows, logs, and moist vegetation. Most return to
natal ponds and
streams to breed. Fertilization is internal; the male provides
a spermatophore which is
picked up by the female and stored in her cloaca.
Fertilized eggs are laid in shallow water
attached to rocks or vegetation.
Young have gills during aquatic larval stage, develop
over 1 or 2 seasons and
disperse into woodland retreats. The lungless salamanders
such as ensatina, slender
salamander and arboreal salamander are completely terrestrial.
Eggs are laid in moist, protected spot and, in some species, guarded by the
mother until
they
are hatched. Development is direct, with no aquatic larval stage. Young are
small
versions of the adults.
Size: 2 1/2 - 3 1/2". Brown above, yellow to reddish
orange below.
lower eyelids, larger eyes and different tooth pattern
than rough-skinned newt. Breeding males
have smooth skin, a flattened tail,
swollen vent area, and dark nuptial pads on the underside of the feet.
Habitat: Grassland, woodland, and forest. During most of the
year these newts are terrestrial. Skin
is rougher and thicker than most
salamanders and they are commonly seen during the day. Logs, rocks
and rodent burrows provide shelter during extreme conditions. Generally safe from predators
because of skin secretions of tetrodotoxin, one of the most toxic substances known. Also found
throughout the flesh and internal organs. Minute amounts can cause paralysis and death in most
vertebrates. If disturbed, newts will assume a “defense posture” which exposes the bright colored
ventral area, presumably as a warning to predators.
Reproduction: Migration to breeding sites begins during the first fall rains. Breeding takes
place from December to May, reaching a peak from February to April. Remarkable homing
ability; newts displaced several miles will still return to the same section of the stream in
which they were spawned. Prefer streams or ponds with rocky beds and tree roots or
other vegetation for cover and egg attachment. Eggs of both species are similar, but
rough-skinned are laid singly while the
hatch from eggs in approximately 4 weeks. Some transform by the end of their first summer.
In cooler areas may remain in the water for another season. Sexually mature at two years
although adults do not
necessarily breed every year.
Food: Insects, earthworms, crustaceans, spiders, slugs, amphibian eggs. Larvae
eat insects and aquatic insect larvae, crustaceans, and
also scavenge.
Arboreal Salamander (Aneides lugubris)
Size: 2 1/2 - 3 1/2". Brown above with pale yellow spots of varying sizes, tail somewhat
prehensile. Young are clouded, with gray speckles and
brassy patches.
Habitat: Primarily oak woodland. Found in hollows, under bark, inside rotting logs or
wall crevices. During summer months may congregate in moist tree hollows high above
the ground. Nocturnal. Active on the ground November to May, except during extremely
cold or dry spells. Lungless, breathes through moist, thin skin which is very smooth. Good
sense of smell which may assist in locating a mate.
Adults can bite.
Reproduction: Eggs laid in arboreal or terrestrial sites and guarded by adult. No free
living larval stage,
development is direct.
Food: Slender
salamanders, insects, centipedes, spiders, sowbugs,
and possibly fungus.
Santa Cruz Black Salamander (Aneides flavipunctatus
Size: 2 5/8 - 3". Uniformly black above and below, sometimes with very small flecks. Young: above
black, limb bases yellow.
Habitat, Reproduction &
Food: Same as Arboreal Salamander
Range: Coastal Mountains of San Mateo, St.
Clara & St. Cruz counties
(Batrachoseps attenuatus)
Size: 3-5 1/2". Very long body and tiny legs.
Sometimes called a worm salamander.
Only 4 toes on each foot. Dark above, with
broad yellow, brownish, or reddish band
on back; colors may vary with locality.
Belly dark, fine specks of white.
Habitat: Grasslands (with trees), chaparral, woodland, forest
and gardens under logs,
boards, leaf litter and streamside rocks. Size and
shape allow it to make use of termite
and earthworm burrows. In defense it will
coil like a watch spring and thrash violently.
Tail may detach if handled
roughly. Lungless, terrestrial.
Reproduction: Breed in late fall and winter during rainy season. 4-21 eggs often
laid in communal nests, young emerge in winter and spring. No
aquatic larval stage,
direct development.
Food: Earthworms, small slugs, mites, spiders, and
small insects such as aphids,
ants, flies, and small beetles.
Ensatina (Ensatina escholtzii)
Size: 1 1/2"-3". Smooth skinned with a swollen looking tail which is
constricted at the base.
Much color variation, but most have yellow or orange
limb bases. Male has enlarged upper lip
and longer, slimmer tail than female.
Habitat: Common in coast redwood, oak woodland, and old chaparral as long as shade
and rotting logs are available. Also make use of woodrat nests and rodent burrows.
Lungless, terrestrial, and primarily nocturnal.
Reproduction: Mates from October to March. Most lungless salamanders engage in
courtship behavior. Males rub and nudge females who straddle the male’s tail. A
spermatophore is deposited, taken up by the female and stored in her cloaca.
Eggs are laid in secure underground sites or under bark or rotting logs. Female broods
eggs. Development is direct,
gills are lost at the time of hatching. Young hatch in summer or fall.
Food: Insects,
earthworms, centipedes, spiders and sow bugs.
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