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How do direct-developing salamanders differ from salamanders with aquatic larvae?
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Caudata
Tiger salamanders (Ambystoma tigrinum) are widespread across much of the United States. Although they are generally black with yellow blotches, bars, spots, or even stripes, some are lighter in colour or have olive markings. Tiger salamanders belong to the mole salamander family, Ambystomatidae.
Salamanders with aquatic larvae and those that undergo direct development differ primarily in their life cycle and reliance on water.12
- Aquatic Larval Stage: Most salamander species have a biphasic life cycle that includes an aquatic larval stage. These larvae are exclusively aquatic, possess external gills, lack eyelids, and have specialized larval dentition. They must undergo metamorphosis—a process involving the loss of gills, the development of eyelids, and skeletal reorganization—to transition into their terrestrial or semiaquatic adult form.3456
- Direct Development: In contrast, species that exhibit direct development, such as most members of the family Plethodontidae, have eliminated the free-swimming larval stage entirely. Their development occurs completely within the egg capsule. When these individuals hatch, they emerge as miniature versions of the adult, possessing either rudimentary gills that quickly disappear or no gills at all. This adaptation allows these salamanders to be entirely independent of standing or flowing water for their reproductive cycle.123