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 This article details the important external morphological features used in the identification of urodelans/salamanders.external morphology of salamanders

Salamandra salamandra (the fire salamander). Original Photo by Dildier Descouens, Source – Wikimedia Commons.

Limbs –

Some aquatic salamanders such as Sirens (Family Sirenidae) and Amphiumas (Family Amphiumidae) have reduced limbs or may have reduced forelimbs and lack hind limbs. Thus the relative size of the limbs and their presence is important in identification.

Feet and Digits -

The digits, along with their relative size and length are also important for identification as they are modified for certain habitats. Digits are longer and their tips may be squarish in climbing species, rock dwelling species may have shorter digits with their ends being blunt. Digits may also have webbing between them.

Tail -

The relative size as well as the shape of the tail are important. In species that are more aquatic (and in larvae) the tail is laterally flattened and may have dorsal as well as ventral fins to increase its surface area to help it swim more easily. The tail can also be prehensile in arboreal salamanders.

Body Colouration -

Body colouration and patterns will help with the process of identification but in most species it will not be enough as there will be multiple colour variations within a species (called colour morphs) and different species may share the same over all body colouration.

Skin -

The skin is smooth in most species but may be have a granular “warty” texture in some species such as some newts.

Skin Glands -

Some salamanders produce alkaloid neurotoxins for self defense and in a few species these toxins can be potentially deadly to humans when they enter the body. The presence and relative size of glands in the skin also help with the identification of salamanders.

external anatomy of larval salamanders

 

Ambystoma mexicanum (axolotl slamander). Original Photo by ZeWrestler. Source – Wikimedia Commons.

External gills -

The relative size and shape of external gills in larvae also vary from species to species and are important for identification. Many aquatic species also retain external gills when they become adults.

 

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References 

Boulenger, G. (1890). Reptilia and Batrachia. Publisher – Taylor and Francis