In the Hamilton Harbour Ecosystem
| In the Hamilton Harbour Ecosystem | |
Introduction to SalamandersThe Salamander is an amphibious species that includes all members from the order Caudata. The name salamander is the common name and is derived from the Arab word meaning "lives in fire". The most abundant salamander family is the Plethodontidae, which contains roughly 200 species, (www.accent.......).
The majority of salamanders are around 12cm in length; and range from brightly to darkly coloured. They are characterized by having short bodies, long tails, four legs with clawless toes, and heads with proportionally large mouths and eyes. Their skin is smooth, moist and contains no external ear openings, (Lamond, 1994). Salamanders are deaf to airborne sounds and hear by sensing vibrations from the ground. They have good vision and a keen sense of smell and taste. Their skin consists of many glands which serve two primary functions. First the glands secrete mucous to keep the skin moist, and second they secrete toxic substances to ward off predators, (Goin, 1978).
Internally, the salamander has a three chambered heart. The respiratory system is typically gills during the larval stages of the life cycle, and lungs in the adult stages. Oxygen uptake can occur through the skin and mouth membranes, (Miller & Harley, 1996)
Salamanders are a component of a balanced ecosytem, and are essential to overall ecosystem health.
Biological and Physiological CharacteristicsGeneral Biological and Physiological
The salamander belongs to the Class Amphibia and the Order Caudata. The following table outlines some common biological characteristics of this classification:
| | Skin secretes mucous and has no hair, feathers, or scales. The larvae are usually aquatic. Each amphibian has a two atrial chambered heart and one cervical and sacral vertebrae. |
| Characterized by a long tail, two pairs of unspecialized limbs, and no middle ear. |
Source: Miller & Harley, 1996.
The remainder of this section deals with specific biological characteristics of the salamander, including: Reproduction, Life-cycle, Body Structure, Feeding, Gas Exchange, Ciculation, and the Nervous System.
Reproduction
Salamanders rely mainly on olfaction and vision when selecting a mate, (www.accent.....). Salamanders are the exception in the Class Amphibia because 90% of all salamanders utilize internal fertilization, (Miller & Harley, 1996). Most amphibians generally use external fertilization techniques. The internal fertilizing salamanders use spermatophores which are capped with sperm. These spermatophores are deposited on a substrate and the female will take the sperm cap with her cloaca. Subsequently, she deposits the sperm cap in a pouch known as the spermatheca. The eggs are fertilized as they pass through the cloaca, and the female will deposit the eggs singly, or in groups, (Miller & Harley, 1996).
Salamanders from the family Plethodontidae (ie. Redback Salamander) lay their eggs on land, usually in cavities in decaying logs or organic matter, (Goin, 1978). Eggs are generally laid in the spring, however the female is capable of storing the sperm for a long period of time so fertilization may take place in the fall or early spring. The female will usually lay 3 to 12 large eggs. These eggs are laid in clusters with each egg attaching to the one which preceded it, (Goin, 1978). The embryos develop rapidly and form large external gills. These gills are never utilized as they are lost at birth. Members of the family Plethodontidae never take an aquatic larval existence, (Goin, 1978).
The members of the Ambystoma family (ie. Spotted Salamander) lay their eggs in aquatic environments, (Bishop, 1943). Fertilization is internal and generally occurs in late March or early April. The female will deposit on average 125 eggs, (Bishop, 1943). These eggs are attached to submarged objects in anywhere from 1 to 6 large masses. The incubation period of the embyos depends on water temperature and can vary from 31 to 54 days. Upon hatching the larvae have gills, no hind legs, and buds as fore legs, (Bishop, 1943). The larvae transform immensley in the first 60 to 110 days of life; growing to an average size of 51mm in this time period. Adult salamanders will reach an average length of between 85 to 100mm, and will reach sexual maturity within two breeding seasons, (Bishop, 1943).
Salamanders in their larval aquatic environment. Notice the external gills and fin shaped tail, necessary for respiration and locomotion in aquatic domains. Return to list of topics in this section.Life-Cycle
The life-cycle of the Redback Salamander is completely terrestrial while that of the Yellow-Spotted Salamander consists of an aquatic larval stage and a terrstrial adult stage, (www.cciw.....). The picture to the left portrays the typical life-cycle of the Yellow-Spotted Salamander (Ambyostoma maculatum) in Hamilton Harbour. Return to list of topics in this section.Body Structure
The skin of salamanders lacks hair, feathers, and scales; it does however, contain glands which secrete a moisturizing mucous. Salamanders are characterized by long tails, four unspecialized limbs, and a relatively flattened skull, (Miler & Harley, 1996).
The vertebral column is modified to provide support and flexibility on land. Salamanders contain both a sacral and cervical vertebrae, which allows for increased pelvic and head support and movement, (Miler & Harley, 1996). The cervical vertebrae allows for the nodding motion of a salamanders head; thereby aiding in prey capture. Salamanders utilize their vertebral and skeletal form to allow for a flexible undulatory type of locomotion, (Miler & Harley, 1996). Terrestrial salamanders generally move in a pattern whereby the alternate movement of appendages results form muscle contractions which throw the body into a curve, (Miller & Harley, 1996). This muscle contraction allows for the advancement of the stride limb. Return to list of topics in this section.
Feeding
Adult salamanders feed largely on invertebrates, while larval salamanders rely heavily on algae and plant material, (www.tapaboy.....). The Plethodontidae family of salamanders use their tongue in prey capture while most other salamanders simply use their jaws, (Goin, 1978). The tongues of salamanders contain glands at the tip which secrete a sticky mucous. This sticky mucous aids in the capture of prey as invertebrates become stuck to the tongues surface, (Miller & Harley, 1996). The salamander will lunge forward toward nearby prey and stick out its tongue to trap the prey. This motion may take as little as 0.05 to 0.15 of a second. Return to list of topics in this section.
Gas Exchange
Gas exchange in salamanders occurs across the skin and through the use of lungs; except for members of the family Plethodontidae who are lungless, (Goin, 1978). The skin of the salamanders is kept moist through the secretions of the mucous glands. This moisture allows for gas exchange to occur across the skins surface. The skin is richly supplied by capillary beds which aid in efficient gas exchange, (Miller & Harley, 1996). Gas exchange across the skin is known as cutaneous respiration. In salamanders, 30 to 90% of gas exchange occurs cutaneously, (Miller & Harley, 1996). Gas exchange may also occur across the moist surfaces of the mouth and tongue; this is known as buccopharyngeal respiration, (Miller & Harley, 1996). The lungs of salamanders are relatively simple sacs and are inflated by the muscles of the mouth and pharynx creating a positive pressure which forces air into the lungs, (Miller & Harley, 1996). Return to list of topics in this section.
Circulation
Salamanders have a two atrial chambered heart with a single non-septum seperated ventricle, (Miller & Harley, 1996). Gas exchange occurs via lungs and skin and therefore blood entering the heart in both the left and right atria is comparably oxygenated. Therefore, to conserve energy when the salamander is submerged (ie. relying solely on cutaneous respiration), blood vessels entering the left atrium from the lungs are constricted, (Miller & Harley, 1996). This adaptation is especially valuable for salamanders that hibernate in mud or in aquatic environments. Return to list of topics in this section.
Nervous System
Salamanders have a brain which develops from three embryological subdivisions. The forebrain controls olfaction and visceral function. The midbrain oversees sensory stimuli and the appropriate motor responses. The hindbrain is involved in motor coordination and in regulating heart rate and respiration, (Miller & Harley, 1996). Salamanders have a lateral-line system responsibilble for detecting low frequency movements in the water, (Miller & Harley, 1996). Salamanders utilize chemoreception, visual, and auditory systems to monitor their environment. They lack a tympanic membrane and middle ear, and most likely only hear sounds which are low-frequency vibrations that get transmitted through the skull to the inner ear and stapes< (Miller & Harley, 1996). Return to list of topics in this section.
Importance in the EcosystemSalamanders represent an integral component of many balanced, healthy North American ecosystems. In recent years, there have been many studies using salamanders to measure the overall health of the environment. Salamanders can act as indicators of environmental stress areas, as their fragile systems are extremely sensitive to manmade pollutants.
Status in Hamilton HarbourIn the Hamilton Region, two species of salamanders are found. These are the Spotted Salamander (Ambystoma maculatum), and the Redback Salamander (Plethodon cinereus), (Brown, 1997 & Lamond, 1994). These species will be dealt with seperately in this section.
The Redback Salamander resides in forest regions of deciduous or coniferous nature. This species prefers rich deciduous upland forests with an undulating topography. The Redback Salamander distribution is defined as abundant and widespread in the Hamilton Area, (Gartshore, 1987). The Redback is most plentiful in two main regions. The first extending east from Ancaster through Dundas and then north through Burlington and Milton and adjacent to Halton Hills. The second is North and South Dumfries, (MAP ONE). These areas are high in abundance due to their geographical status. Both these areas contain extensive woodland and varied topography; ideal conditions for this species of salamander. The Redback can be found in the urban areas of Hamilton, Stoney Crek, and Burlington; mainly along the escarpment and in ravines. The Redback is a nocturnal salamander. During daytime hours it is commonly found in areas exhibiting moist conditions. Specifically, it is common under logs, rocks, and leaves, as well as within rotting vegetation, (Garthshore, 1987).
The Yellow-Spotted Salamander inhabits both deciduous and coniferous forest land. They preferentially select woodlands with well-drained upland areas which are adjacent to breeding pools. The Plethodon cinereus commonly occurs throughout Ontario, ranging as far north as 50 degrees north latitude and as far west as 91 degrees west longitude. Five main regions are common for the prescence of the Spotted Salamander: central Milton, Dundas Valley, North/South Dumfries, northeast section of Six Nations I.R., and central Haldimand, (Garthshore, 1987), (MAP TWO). Several unexpected sitings of the salamander have been noted. In a few cases, the species has been found in small woodlots that are extremely isolated from other woodland regions. This species has also been found in small ravine environments of urban Mississauga and Oakville. After completing their reproductive responsibilities most adults will leave the breeding ponds and reside in underground burrows. These burrows will also serve as the salamanders winter home for hibernation, (Garthshore, 1987).
Distribution of the Redback Salamander in the HamiltonThe following map depicts the distribution of the Redback salamander in the Hamilton Region. The black dots indicate regions where the Redback is commonly found.
 |
Distribution of the Yellow-spotted Salamander in the HamiltonThe following map depicts the distribution of the Yellow-spotted salamander in the Hamilton Region. The black dots indicate regions where the Yellow-spotted is commonly found.
 |
Salamander Picture GalleryThe Yellow-Spotted Salamander (Ambystoma maculatum), found typically in the Hamilton region. This species prefers woodland areas of well-drained uplands, adjacent to breeding pools. This salamander exists in both an aquatic larval stage and terrestrial adult stage. Return to Status in Hamilton Harbour
This picture depicts a Redback Salamander (Plethodon cinereus), which are common in the Hamilton Region. This species prefers rich decidous forests of undulating topography. Return to Status in Hamilton Harbour
This picture potrays a salamander in its larval stage. Like most salamanders, except those from the family Plethodontidae, these larvae exist in aquatic environments. Notice the external gills and fin shaped tail necessary for respiration and locomotion in aquatic domains.
Check Out Some Other PagesThe following are some other pages which I found informative and helpful when conducting my research:
Bishop, S., 1943. Handbook of Salamanders - Volume III. Comstock Publishing Company Inc., New York. Pages143-147, 232-236.
Brown, J., 1997. The establishment of an amphibian monitoring protocol and the collection of baseline data in order to evaluate the status of amphibian populations in Cootes Paradise. Fourth Year Unpublished Biology 4C09 Thesis.
Environment Canada, 1996. Great Lakes Fact Sheet: Amphibians and Reptiles in the Great Lakes Wetlands: Threats and Conservation. Published by Authority of Minister of Environment; pp 1.
Gartshore, M.E., 1987. Annotated Checklist to the Herpetofauna of Haldimand-Norfolk. The Natural Areas Inventory of the Regional Municipality of Haldimand-Norfolk, Vol III. The Norfolk Field Naturalists, Simcoe.
Goin,C., Goin O., Zug G., 1978. Introduction to Herpetology - Third Edition. WH Freeman & Company, San Francisco. Pages 90, 154,157, 210-212.
http://www.cciw.ca/glimr/
http://tapaboy.ma.ultranet.com/~anvil/newt/news/index.html
http://www.accent.net/kaymur/salamr2a.htm
Lamond, W., 1994. The Reptiles and Amphibians of the Hamilton Area. Published by The Hamilton Naturalists' Club, Hamilton. Pages 41-44, 49-52.
Miller & Harley,1996. Zoology - The Animal Kingdom Wm. C. Brown Publishers, Toronto. Pages 272-284
