Question

Compare and contrast the reproduction, brooding strategies and life cycle of anurans (frogs and toads) and urodeles (newts and salamanders).

Answer 1

Anurans:-

Reporduction

Most anurans have external fertilization, and adopt a mating posture called amplexus to insure contact between eggs and sperm. There are exceptions even to this rule of anuran reproduction, which points to the extreme diversity of reproductive modes found in this animals

Brooding strategy

Brooding in anurans involves retaining the eggs and/or larvae on the body of the parent for a longer period of time than that required to simply transport the larvae from a nest site to an aquatic site. A variety of behaviors can be observed among the many species that exhibit brooding

Life cycle

It includes three stages: Egg, larva, and adult

The life cycle of a frog consists of three stages: egg, larva, and adult. As the frog grows, it moves through these stages in a process known as metamorphosis

Urodeles:-

Reporduction

Adults exhibiting this pattern lay eggs in water, where they hatch into free-living larvae. Unlike anuran tadpoles, the young urodeles emerge from the egg as aquatic larvae with external gills and already have four limbs emerged.

Brooding

When breeding periods are short, males aggregate and scramble for matings by interfering with one another's attempts to inseminate females. Unattended, developmentally advanced eggs of the mountain dusky salamander (Desmognathus ochrophaeus Cope) lost more water/hour than unattended, recently oviposited eggs. However, advanced eggs contained significantly more water than recently oviposited eggs; due to their smaller surface area/volume ratio, advanced eggs lost a smaller percentage of their total water during the test period. For both groups, the presence of the female significantly reduced water loss from the eggs. Since water loss was similarly reduced when an inanimate object was wrapped about the eggs, it appears that the female decreases clutch desiccation by reducing the exposed surface of her egg mass.

Life cycle

Apart from cutaneous respiration present in all species, most lissamphibians are born in an aquatic larval stage with gills. After metamorphosis they develop lungs to breathe on land. The larvae of urodeles and apods present external, filamentous and highly branched gills which allow them to breathe underwater.