Amphibian families
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Contents
Order
Anura - Frogs and Toads
This order of amphibians includes the frogs and toads. Five families belonging to the order Anura occur in Canada: Ascaphidae, Pelobatidae, Bufonidae, Hylidae and Ranidae. These families of frogs and toads have characteristics which distinguish them from other families.
The five families of frogs and toads have different characteristics but show a similar body form:
- compact body;
- four legs;
- hind legs have 5 digits and are stronger than the forelegs;
- forelegs have 4 digits;
- there is no tail;
- large head;
- lack of a distinct neck;
- hump on the back;
- lidded eyes;
- paired small nostrils;
- no claws on the toes;
- thin moist skin;
- teeth on upper jaw
Traits of the Order Anura. (Source: Canada's Aquatic Environments) The distinction between frogs and toads is imprecise. Frogs tend to be moist, slimy and jump, whereas toads tend to be warty, dry and walk. Toads can tolerate drier conditions and have warts and poison glands that contain toxins. Toad warts do not cause warts, but some toxins produced by toads cause heart failure, while others affect the central nervous system. Frogs and toads also differ in the way they lay their eggs. Most frogs lay their eggs in globular masses, while toads lay their eggs in strings.
Family
Ascaphidae - Tailed Frogs
Wood frog (Hyla versicolor) egg mass. (Source: Canada's Aquatic Environments) 
Toad eggs. (Source: Canada's Aquatic Environments) Number of Species in the World
There is only one species in this family:
- Tailed frog (Ascaphus truei)
Identifying Characteristics
Tailed frogs do not actually have a tail, but males possess a tail-like copulatory organ that enables these frogs to practice internal fertilization, unlike any other frog. Other unique characteristics include ribs that are not fused to the backbone and the presence of tiny tail wagging muscles, remnants of their evolution from tailed ancestors. They have vertical eye pupils, a characteristic shared by only one other family (Pelobatidae).
Feeding
These frogs are restricted to fast flowing streams where they feed on terrestrial and aquatic insects. Because their tongues are attached to the back of their mouths, they can not flip it out of their mouths to catch flies like most other frogs. Instead, they prey on terrestrial and aquatic insects.
Mating
Tailed frogs are unique because they fertilize their eggs internally. During breeding season, males also develop black pads on the palms of their front feet, their arms, and their upper chest. The tadpoles have a sucker-like mouth disc to cling to the surface of rocks in a swift flowing stream.
Pelobatidae - Spadefoots
Number of Species in the World
There are 64 species of spadefoots worldwide,
Identifying Characteristics
Although they are squat, short legged and have warty skin like true toads, the spadefoots are not toads because they lack parotid glands and vertical eye pupils. They are called spadefoots because of a single, sharp-edged, black spade on each hind foot that enables them to burrow down into the ground. In contrast, true toads have two tubercles on their hind limbs for digging.
Feeding
Outside of the breeding season, adults emerge from their burrows to forage on insects, especially on rainy nights. The tadpoles feed primarily on algae, but sometimes become cannabalistic.
Mating
Spadefoots are explosive breeders, taking advantage of temporary ponds and pools formed after heavy rains in late spring and early summer. Hatching and development of the tadpoles takes only a few weeks, an important adaptation in arid sites where breeding ponds dry up quickly.
Canada
There are only 2 members of this family in Canada, both of the genus Scaphiopus:
- Great Basin spadefoot (Scaphiopus intermontonus)
- Plains spadefoot (Scaphiopus bombifrons)
Bufonidae - True Toads
Number of Species in the World
The family Bufonidae represents the true toads and includes 20 genera and 279 species worldwide. Seventeen of these species occur in North America.
Identifying Characteristics
Members of this family possess a prominent cranial crest, extremely warty and dry skin, large parotoid glands on either side of the neck and no true teeth. The parotid glands and the warts secrete a sticky white poison which deters predators. These poisons cause irritation to the eyes and mouth and if swallowed can cause illness, but there is no danger in handling toads. Contrary to popular belief, toads do not cause warts.
Feeding
These toads are voracious eaters and learn to wait under outdoor lights for insects that are attracted to the illumination.
Mating
Toads are most often seen during the breeding season in the spring and early summer when large numbers congregate in shallow, temporary pools. The males call for mates, their vocal sac inflating to various shapes depending on the species. A male may cling to the female for days until she lays her eggs, usually in pairs of strings attached to vegetation. No other four-footed vertebrate lays more eggs than female toads which may lay as many as 25,000. The eggs hatch into tiny black tadpoles that metamorphose a few weeks later into toadlets.
Canada
There are five members of the Bufonidae family in Canada, all of the genus Bufo:
- American toad (Bufo americanus)
- Fowler's toad (Bufo fowleri)
- Canadian toad (Bufo hemiophrys)
- Western toad (Bufo boreas)
- Great Plains toad (Bufo cognatus)
Hylidae - Tree Frogs
Number of Species in the World
The family Hylidae represents tree frogs and chorus frogs, of which there are 600 species worldwide.
Identifying Characteristics
These frogs are small, slim and vary in colour, with some changing colour according to their environment. Not all species are tree climbers, but they do have enlarged adhesive pads at the tip of each toe and their legs are long and slender. Through evolution, some species have lost most of the adhesive pad and remain close to the ground, climbing only to low heights. Tree frogs have extra cartilage between the pad and the rest of the digit to help the muscles in lifting the pad. Tree frogs often have flash colours on their hind legs and at the side of their body. These patches of colour catch the attention of the predator's eye when it leaps, but when the frog lands and folds its legs the colour disappears and the predator loses sight of its prey.
Feeding
These frogs eat insects in an arboreal environment. The tree-climbing members of the family have adhesive toe discs to help them manoeuver as they find food.
Mating
After mating, the eggs are laid singly or in small globular masses in open water in temporary or permanent ponds. The tadpoles develop rapidly and transform between June and September into froglets and sexual maturity is reached within 1 to 2 years. Males have paired or single vocal pouches.
The members of this family belong to three Genera: Acris, Pseudacris and Hyla
Genus Acris
These frogs are nonclimbing members of the tree frog family. They are very small frogs with a warty appearance and extensively webbed toes. They have a distinctive "V"-shaped spot between the eyes and longitudinal stripes on the thigh.
Genus Pseudacris
This genus contains chorus frogs, which gain their name from their extended spring chorus, sometimes extending for as long as 2 months. Chorus frogs are ground dwellers and are the first frogs to appear in spring.
Genus Hyla
Like other true tree frogs, this genus has an enlarged pad at the tip of each toe and its members are efficient climbers.
Canada
There are six species of Hylids found in Canada:
- Cricket frog (Acris crepitans)
- Spring peeper (Pseudacris crucifer)
- Striped chorus frog (Pseudacris triseriata)
- Diploid grey tree frog (Hyla chrysoscelis)
- Tetraploid grey tree frog (Hyla versicolor)
- Pacific tree frog (Hyla regilla)
Ranidae - True Frogs
Number of Species in the World
The family Ranidae represents true frogs and contains 560 species worldwide and 8 species in Canada. This family has 50 genera in the world.
Identifying Characteristics
These are large frogs that have a bony breastbone, dorsolateral folds, a distinct tympanum, and long legs with extensive webbing on the hind feet. They are excellent jumpers and typically live on the water's edge, entering it to mate, catch insects, or flee from predators.
Feeding
These frogs are carnivorous, eating insects, spiders, and crustaceans. The larger species even eat small mammals, birds, and frogs.
Mating
Mating occurs in the spring, beginning with the males calling in chorus. Females lay up to 20,000 eggs which hatch within a month. Tadpoles metamorphose into froglets in 6 to 24 months, depending on the species.
Canada
Eight species in the genus Rana occur in Canada:
- Bullfrog (Rana catesbeiana)
- Green frog (Rana clamitans)
- Pickerel frog (Rana palustris)
- Northern leopard frog (Rana pipiens)
- Mink frog (Rana septentrionalis)
- Wood frog (Rana sylvatica)
- Red-legged frog (Rana aurora)
- Spotted frog (Rana pretiosa)
Order
Caudata - Salamanders
Traits of the Order Caudata. (Source: Canada's Aquatic Environments) There are 336 species of tailed amphibians in the world. These families of salamanders have characteristics which distinguish them from other families, but they are all voiceless, nocturnal and carnivorous. Salamanders are slow moving and solitary, only coming together for mating.
The different families of salamanders have similar body form
- slender body;
- long tail;
- 4 legs of equal length;
- hind feet have 5 digits (exception: four-toed salamander);
- fore legs have 4 digits;
- lidded eyes;
- costal grooves;
- no claws on toes;
- thin moist skin;
- teeth in upper and lower jaw;
- lack a urinary bladder
Family
Proteidae - Mudpuppies
Number of Species in the World
The family Proteidae represents mudpuppies and waterdogs, containing 6 species worldwide.
Identifying Characteristics
Members of this family are permanently aquatic, living in streams, lakes, and ditches. They retain feathery red gills throughout their life and have 4 toes, rather than the usual 5 on the rear foot. They have a stout body, with relatively weak legs, and a short tail that is less than 1/3 of their body length.
Feeding
These salamanders are carnivorous and eat aquatic insects, worms, molluscs, frogs, and other salamanders.
Mating
After mating, the female lays 18 to 25 eggs singly on submerged objects.
Canada
In Canada, this family is represented by one genus and a single species:
- Mudpuppy (Necturus maculosus)
Ambystomatidae - Mole Salamanders
Mole Salamanders. (Photograph by Lorelei Girouard) Number of Species in the World
The family Ambystomatidae represents mole salamanders and contains 33 species worldwide and 7 species in Canada.
Identifying Characteristics
Members of this family of salamanders are chunky, largely terrestrial, and live under leaf litter, stones and logs, or in the burrows of other animals. They are called mole salamanders since they burrow underground. Species in this family have well developed costal grooves, 4 sturdy limbs and 4 toes on each front foot, with 5 on each rear foot. This family of salamanders can be difficult to distinguish from members of the family Plethodontidae, but an identifying sign is the absence of a groove running between the lip and the nostrils.
Feeding
These salamanders look for their food on land and eat earthworms, insects, and molluscs.
Mating
Breeding occurs in early spring in temporary pools. In shallow water, small colourless eggs are laid singly, in small clusters, or in globular masses. The eggs hatch within a few days to a week and the tadpoles transform into juveniles by July or August.
Canada
All seven members of this family found in Canada belong to the genus Ambystoma:
- Jefferson's salamander (Ambystoma jeffersonianum)
- Blue-spotted salamander (Ambystoma laterale)
- Yellow-spotted salamander (Ambystoma maculatum)
- Smallmouth salamander (Ambystoma texanum)
- Tiger salamander (Ambystoma tigrinum)
- Northwestern salamander (Ambystoma gracile)
- Long-toed salamander (Ambystoma macrodactylum)
Dicamptodontidae - Giant Salamanders
Number of Species in the World
The dicamptodontids are ambystomid-like salamanders, but have different internal bone structure and habitat use. There is only one species of this family in Canada, but worldwide, there are five species in two genera.
Identifying Characteristics
The dicamptodontids have a similar, chunky appearance to the members of the family Ambystomidae, but their costal grooves are often inconspicuous. This family has North America's largest and smallest highly aquatic species. They inhabit cold streams and are rarely found away from water throughout the year.
Feeding
These salamanders feed voraciously on invertebrates. The larger members, such as the Pacific Giant salamander, eats deer mice, shrews, and other small mammals.
Mating
These amphibians lay unpigmented eggs in secluded, well concealed aquatic sites. Their eggs are laid in clusters in streams. Larvae have reduced gills and fins for living in fast streams.
Canada
There is only one representative of this family in Canada:
- Pacific Giant salamander (Dicamptodon ensatus)
Plethodontidae - Lungless Salamanders
Number of Species in the World
The lungless salamanders are the most diverse family of salamanders, represented by 225 species in the world. Most are terrestrial, living under rocks, logs and in animal burrows, but aquatic habitats are necessary for breeding.
Identifying Characteristics
Adults are small, slender and have prominent costal grooves, as well as a groove from the lip to the nostril which conducts substances to the nostrils to aid in olfaction. These salamanders live in moist environments and they lack lungs, but breathe through their skin and the lining of their mouths. The loss of buoyant lungs was an ancestral adaptation to life in mountain streams.
Feeding
Members of this family eat a variety of insects in a diversity of habitats.
Mating
The pattern of mating in this family varies between genus and species, since some lay eggs on land and others in water, and juveniles may develop in water or on land. Mating occurs in the fall, winter or spring, and eggs are deposited in the spring or summer.
Genus Hemidactylium
These are the four-toed salamanders. Their eggs are laid on land and hatch into aquatic larvae, which later transform into terrestrial adults.
Canada
One species of this genus is found in Canada:
- Four-toed salamander (Hemidactylium scutatum)
Genus Plethodon
Members of this genus are also known as woodland salamanders. They have no striking features and are actually recognized by the absence of features found in other salamanders. The species in this genus are medium-sized and have 5 toes on each hind foot. The eggs are laid on land in moist woods and the aquatic larval stage, common to most salamanders, is omitted. Juveniles hatch as miniatures of the adult, from eggs laid in the late fall, having passed the gill stage in the egg.
Canada
Two species of this genus are found in Canada:
- Eastern red-back salamander (Plethodon cinereus)
- Western red-back salamander (Plethodon vehiculum)
Genus Desmognathus
These salamanders are known as dusky salamanders, but their colouring and patterning are extremely variable. Three features are always shared; the shape of the tail, the size of the transformed individual, and geographical location. They have a pale line from the eye to the angle of the jaw, but this marking is not always visible in old or dark individuals. These salamanders can jump several times their own length in an effort to escape. They are not found in large streams with predatory fish, but are common in brooks, springs, and mountain cascades.
Canada
One species represents this family in Canada:
- Dusky salamander (Desmognathus fuscus)
Genus Ensatina
There is only one member of this genus, but there are a number of recognized subspecies. This salamander is also known as Eschscholtz's salamander. In general, they are darkly coloured with variations of blotches or patterns of black, orange or yellow. They prefer moist, forested habitats. In Canada, they are only found in the extreme southwest of British Columbia.
Canada
One species is found in Canada:
- Oregon ensatina (Ensatina eschscholtzi)
Genus Aneides
These are known as climbing salamanders because some live in trees and are excellent rock climbers. They have well developed limbs, long toes and a prehensile tail, all used for efficient climbing. These salamanders have distinct costal grooves and well developed jaw muscles, which give the head a triangular shape.
Canada
There is only one species in Canada:
- Clouded salamander (Aneides ferreus)
Genus Gyrinophilus
These are red or salmon coloured salamanders with black spots, commonly known as spring salamanders. They prefer clear, cold water in forests or rushing mountain brooks. They also occupy soggy or damp terrain.
Canada
There is only one species in this genus occurring in Canada:
- Spring salamander (Gyrinophilus porphyriticus)
Genus Eurycea
Commonly known as brook salamanders, they live in brooks, springs, river bottom swamps and other small bodies of water where there are few predatory fish. Most are yellow in colour, especially on the belly. Their larvae are aquatic. During the breeding season, males have well pronounced downard projections from the nostrils. There are three types of brook salamanders: the "typical" brook salamanders wander into moist woodlands in wet weather, the "long-tailed" brook salamanders have tails that are over half the length of their bodies and the "neotenic" brook salamanders retain larval characteristics (external gills) throughout adulthood and are completely aquatic.
Canada
There is only one species in Canada, a typical brook salamander:
- Two-lined salamander (Eurycea bislineata)
Salamandridae - Newts
Number of Species in the World
The family Salamandridae represent newts and contains 56 species worldwide, but there are only 2 species in Canada.
Identifying Characteristics
Members of this family are called newts. Newts are relatively small and have no costal grooves, but their skin secretes a poison that helps protect them against predators. The newt family comprises two groups in North America: the western newts (genus Taricha) and the eastern newts (genus Notophthalmus). The two genera differ in colouration, with the western newts being uniform in colour and the eastern newts being spotted or striped.
Feeding
Members of this family eat insects, worms, small crustaceans, and molluscs.
Mating
Mating behaviour among the Salamandridae is variable. They spend their early life as larvae in water, their juvenile stage on land, and their adult life partly or completely in water.
Canada
In Canada, there are two species of newts.
- Red spotted newt (Notophthalmus viridescens)
- Rough-skinned newt (Taricha granulosa)
