Urodela – Salamanders
They only four-limbed animals that can grow back entire limbs and regenerate organs when injured
A slim body, four legs, and long tails are the characteristics of newts and salamanders. Preferring dark and wet places, they can be aquatic, terrestrial, or amphibious as adults and have complicated life cycles. Salamanders and newts cannot be distinguished scientifically.
Inhabiting primarily nocturnal niches, these amphibians have evolved various survival strategies. Many species employ vivid and eye-catching colors as a warning signal to potential predators, indicating their toxicity. In contrast, some adopt the art of mimicry, resembling the patterns of their toxic counterparts to deter would-be attackers.
These amphibians can remarkably regenerate lost body parts, including limbs and even parts of their heart and spinal cord. Some, like the axolotl, never fully undergo metamorphosis, remaining in a neotenic state throughout their lives, characterized by their permanent aquatic lifestyle.
Another astonishing feature is their production of potent toxins. Certain newt species possess skin glands that contain tetrodotoxin, an extremely potent toxin that can be deadly to predators if ingested. This chemical defense has earned them the nickname “fire salamanders,” as their toxins can cause a burning sensation when touched.
Furthermore, newts and salamanders are highly sensitive to environmental changes, making them crucial indicators of ecosystem health. They are often referred to as “bioindicators” because their presence or absence in a given habitat can signal changes in water quality and overall environmental conditions.
Within this order, courtship rituals are intricate and captivating, often involving elaborate displays by males to attract the attention of females. In some cases, males undergo color changes to enhance their allure during mating season, adding a fascinating dimension to the reproductive behaviors of these remarkable amphibians.
Families in this order
Advanced salamanders
Largest family of salamanders, 216 of which are Threatened as of 2020. 2 species are extinct (years 1964, 2019)
All newts are salamanders, but not vice versa: newts spend more of their adult lives in the water
Native to US and Canada; members in this family are mostly terrestrial
Unlike other salamanders, they never lose their gills, allowing them to spend their lives underwater
Unique in having small forelimbs and no hind limbs & external gills; only salamanders known to eat plants
Endemic to the North-west US; until 1992 were classified in family Ambystomatidae
US native, these legless aquatic salamanders have elongated, greyish-black body
Primitive salamanders
Practice external fertilization that look like that someone crossed a frog with a lizard
Nearly 1.8 m (6 ft) in length and living up 60 years, these “living fossils” are the largest of the amphibians