Grotto Salamander

Media
Image of a grotto salamander
Status
Name
Species of Conservation Concern
Scientific Name
Eurycea spelaea
Family
Plethodontidae (lungless salamanders) in the order Caudata (salamanders)
Description

Adult grotto salamanders are pale tan to pale pink. A cave-dweller, this species lacks gills in the adult form and is partly or completely blind. The head is rather wide and flat. The tail is long, slender, and finless. There are 16–19 grooves along the side. The eyes are small and reduced, covered or partially covered by a fusion of the eyelids. The eyes may appear sunken into the head.

The larvae have gills, functional eyes, and broad tail fins; they have more pigment than adults, being brown to dark gray, sometimes with spots or streaking on the sides and tail.

A unique characteristic of the lungless salamander family is the presence of a groove in the skin running from each nostril down to the lip. This groove (the naso-labial groove), in some species, is associated with a projection of skin that extends the groove below the upper lip (looking vaguely like a tiny fang). The two groove-extending projections are called cirri and are more pronounced on adult males. The grooves and cirri may be associated with the sense of smell, specifically for detecting pheromones (scents emitted by females).

Similar species: There appear to be three genetic lineages of grotto salamanders, suggesting distinct species within the distribution of the species as it is currently understood. Missouri has two distinct lineages that may soon be elevated to full species status:

  • The northern lineage, or northern grotto salamander (Eurycea nerea), occurs mainly in the Salem Plateau of central and southern Missouri
  • The western lineage, or western grotto salamander (Eurycea spelaea), occurs in the Springfield Plateau of southwestern Missouri.

The third, southern lineage, the southern grotto salamander (Eurycea braggi), occurs in northern Arkansas and not in Missouri.

Genetic testing is the certain way to distinguish between these lineages, but because they are found in different regions, geography is the most practical way of separating them.

Size

Adult length: 3–4¾ inches; occasionally to 5¼ inches.

Where To Find
Grotto Salamander Distribution Map

Occurs in wet caves in Missouri's Ozark Highlands region. It is endemic (completely limited to) the Ozark Highlands; in addition to its Missouri range, the only other places it occurs is in northeastern Oklahoma, northern Arkansas, and a single county in extreme southeastern Kansas.

This is the only species of blind salamander in Missouri, occurring only in Ozark wet caves. Adults are true troglobites, living in total darkness and requiring caves with a spring or stream running through them.

The larvae, which possess functional eyes, can occur in small streams and springs outside of caves.

Because of the delicate balance of cave ecosystems, grotto salamanders and their cave and spring habitats need to be protected from human disturbance, overcollecting, and water and groundwater pollution.

Adults eat mainly small aquatic and terrestrial invertebrates, as well as the larvae of other Eurycea salamanders. Grotto salamanders occur in greater abundance in caves with many bats, probably because they feed on insects attracted to the bat guano.

The larvae eat many types of small freshwater aquatic invertebrates, such as amphipods (scuds), isopods (pillbugs), copepods (such as cyclops), and so on. The larvae have also been known to occasionally consume bat guano to supplement their diet.

A Missouri species of conservation concern because of its extremely restricted range in Ozark highland karst (cave and spring) habitats; its relatively low population size; its affinity to cave ecosystems; and our limited information on basic biology.

The survival of this species requires healthy cave ecosystems, which in turn require clean groundwater and lack of disturbance by humans.

Life Cycle

Reproduction in grotto salamanders is not well studied due mainly to their secretive habits in caves. Apparently, adults mate during the late spring into the summer months due to an influx of nutrients (in the form of bat guano) that support this period, when the salamanders require their greatest food supply.

Fertilization is internal (as with most salamanders), and females apparently lay eggs within 1 to 4 months after mating. The eggs are probably attached to stones in or near water in caves. The larvae are aquatic and normally inhabit cave streams; sometimes, however, they are found in springs or streams that flow out of caves. They may take 2–3 years to transform into adults. A study in Oklahoma showed them taking up to 6 years to transform into adults. The estimated lifespan in the wild is at least 9 years; in captivity, nearly 10.

Human activities on the surface of the land can have profound impacts in cave systems below. Pesticides, fertilizers, and other chemicals can drain from the land into sinkholes and into cave systems. When land is disturbed, silt can also wash into cave systems, altering those sensitive environments. Learn about vegetated buffer zones around sinkholes and other karst features, erosion and sediment controls, and other habitat best-management practices.

These smooth, graceful, pink salamanders remind us of the overall delicacy of their cave ecosystem. It is important to be extremely careful to respect caves, their inhabitants, and the archaeological artifacts they contain.

In the unique ecosystem within a cave, grotto salamanders function as predators to insects and other small prey. Meanwhile, they and their eggs and larvae serve as prey to larger creatures, such as mammals venturing into caverns. Even their bodies, after they die, serve as nutrients for future cave life.

The adaptations and geographical distribution of the grotto salamander have many parallels with other cave-dwelling animals, including cave crayfish, cavefish, and certain sculpins.

This is a member of the lungless salamander family (Plethodontidae). It’s a large family with 27 genera and about 443 species. The family probably originated in the southern Appalachian Mountains; its members now occur over the eastern half of North America, the West Coast, and into Mexico, Central America, and northern South America. A few species also occur in southern Europe and South Korea.

The lungless salamander family is named because the adults lack lungs and most lack gills; the oxygen they require is taken from their environment through the skin and mucous membrane of the mouth.

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About Reptiles and Amphibians in Missouri
Missouri’s herptiles comprise 43 amphibians and 75 reptiles. Amphibians, including salamanders, toads, and frogs, are vertebrate animals that spend at least part of their life cycle in water. They usually have moist skin, lack scales or claws, and are ectothermal (cold-blooded), so they do not produce their own body heat the way birds and mammals do. Reptiles, including turtles, lizards, and snakes, are also vertebrates, and most are ectothermal, but unlike amphibians, reptiles have dry skin with scales, the ones with legs have claws, and they do not have to live part of their lives in water.