General Topics

Caves of Missouri

Cave Geology

Information from (Weaver, H. Dwight)

Steps to an Ozark Cave’s Formation:

  1. The high sea levels of the Paleozoic Era deposite limestone (CaCO3) and dolostone ((Mg,Ca)CO3) layers in the region; later, uplift produced the Ozark dome, a karst region.
  2. Rain collects CO2 from the atmosphere and from decomposing organic materials on the surface. This reacts with the water to produce carbonic acid, H2CO3.
  3. The acidic water seeps into the groundwater through joints, fractures, or by absorption of water from a loosing stream or disappearing stream.
  4. The carbonic acid in the groundwater dissolves the cement material that holds limestone and dolostone together, dissolving the rock. As the space enlargens and the water table subsides, the water turbulence from cave streams and the abrasive force of carried particles help to accelerate the cave-formation process.
  5. This process produces caves, sinkholes, and pits.
  6. Cave features such as speleothems grow when the water table recedes from the cave while water continues to drip through the bedrock into the air-filled chamber.

Cave Features

Crystalline mineral deposites, otherwise known as speleothems, form as a result of a retreating and encroaching water table level and the resulting mineral deposition. As the percolating acidic water collects carbon dioxide and dissolves the limestone/dolomite bedrock, it also accumulates minerals such as calcite, aragonite, nitrates, sulfites, and metal oxides–these are the building blocks for speleothem deposites. As the water breaches the aerated cave, a CO2 gradient between the water and the air forces the CO2 out of solution, which subsequently triggers mineral deposition.

The color of these mineral deposites is results from impurities that stain the crystal. For instance, iron oxide produces a red or orange coolor, manganese oxide produce black, charcoal, blue, or gray, and copper produces a blue-green color. These can be great beauties but they are also very vulnerable to the human touch, water pollution, and erosion.

The two major categories of speleothems are the stalctite, which hangs from the ceiling, and the stalagmite, which grows from the floor.

(image from Wikimedia Commons; “Naracoorte-cave” https://commons.wikimedia.org/wiki/File:Naracoorte-cave.jpg)

One example of a stalactite is known as the “soda-straw”; this forms a hollow tube as the water droplets cool quickly and crystallize on the outside and then pour farther down the tube. (hint: look for the small bulge of water poking out the tip).

Stalagmites form as the water falls from the ceiling to the floor and deposits minerals; because of the dripping element, they can be uneven or pitted or ridged. Sometimes, a column will form with the merging of a stalactite and stalagmite.

Other times, flowstone features form as saturated water flows along the walls of the cave; they can even preserve animal bones. Curtains or draperies, examples of flowstone, form beatuiful thin sheets that are often banded with iron impurities along the ceilings of caves by this process.

(image from Wikimedia Commons; “Stone curtains on display at Reed Flute Cave” https://commons.wikimedia.org/wiki/File:Stone_curtains_on_display_at_Reed_Flute_Cave.JPG)

In the streams on cave floors, small variations in the stream bed trigger calcite deposition. This can produce dam-llike features called rimstone dams. This will cause pooling of the cave streams.

Helictites are contorted features whose peculiar shape comes from variations in the crystalline structrure of the disposited carbonate minerals. In some ways they resemble tree roots.

(image from Wikimedia Commons; “Helictites at Jenolan Caves” https://commons.wikimedia.org/wiki/File:Helictites_at_Jenolan_Caves.jpg)

The gypsum family of cave formations forms from hydrous sulfate minerals that compse the colorless selenite crystals. One category of gypsum crystals are needles, fragile and nearly invisible pins on the floor. The needles stretch up from the floor because this represents the direction of crystallization most preferable and easiest for the shape and structure of the crystal lattice of the minerals. Similar to needles are gypsum hairs, which tend to grow out of fractures in the cave ceiling or floors. Again, they crystallize along the cracks because these are the easiest paths for growth.

Gypsum flowers are gorgeous features that form similarly to the other gypsum varieties. Its curved nature derives from the uneven growth rates between the center of the flower and the edges.

(Image from Wikimedia Commons; “Gypsum speleothem (Cleaveland Avenue, Mammoth Cave, KY)”   https://commons.wikimedia.org/wiki/File:Gypsum_speleothem_(Cleaveland_Avenue,_Mammoth_Cave,_KY.jpg)

Caves as Records of Past Environmental Conditions

(Information from Schwarcz, H. P.)

Unlike the dymanic surface environment, the conditions inside a cave, such as temperature and humidity, remain almost stagnant. The only vaiable is the mineral and chemical contents of the water seeping through the caves and forming the deposits, resulting from changes in climate and in the types of organic activity on the surface. Thus, when these minerals are deposited or carried into caves, they can remain unaltered for many thousands of years, creating a geologic record of past environmental conditions.

For example, speleothems can contain rings that represent different periods of time: the chemical composition of each ring will disctate its characteristics and can be analyzed in order to understand the past environments and their ages.

Sometimes, skeletons or pollen can get trapped in the flowstone or detrital sediment, providing glimpses of the ancient ecosystems present. Commonly found skeletons include bats and microorganisms that are preserved in the soil.

Furthermore, simply the erosional carving of the cave walls by water can illustrate groundwater levels and water flow rates across the timescale. Specifically, high water discharge through caves would produce wider caves while low intensity streams that flow through caves will only erode narrow channels. In addition, the extent of sediment deposits can reveal erosional circumstances on the surface and water flow through the cave.

In terms of relaying information about the current environmental conditions, the condition of the very sinsitive cave organisms provide a good warning when water pollution is entering our groundwater supply. For example, the cave fish population will not thrive in the presence of toxic fertilizers, garbage contamination, or other water pollutants that are carried underground by the percolating water. They can also be affected by the removal of key nutrients from the surface above, as this is a primary energy source for cave life. In addition to nutrients, the cavefish require adequate water supply through the cave system: man-made dams that divert water resources for irrigation purposes have negatively impacted the cavefish’s habitat and added to the causes of its threatened status. Therefore, it is important to be consious about the chemicals we use in agriculture so our water supply isn’t contaminated. We can also protect and maintain barriers to soil erosion, such as vegetation, to prevent valuable nutrients from washing away. (“Eyeless ‘Ghost Fish’ Haunts Ozark Caves.”)

For a complete study on the effects of water pollution, mainly by organic waste, on cave ecosystem dynamics, click here.

Citation: Graening, Gary O., and Arthur V. Brown. “Ecosystem Dynamics and Pollution Effects in an Ozark Cave Stream.” Journal of the American Water Resources Association, Dec. 2003. wwww.csus.edu/indiv/g/graeningg/pubs/jawra_39_6_1497-1507.pdf.

Cave Restoration

Information from “Cave Restoration” by William R. Elliot and Jonathan B. Beard: Conserving Missouri’s Caves and Karsts.

Due to the extensive touring and vanadlism of Missouri caves, many caves have broken stactites and stalagmites, grafitti on the wall, and contaminated cave deposits from contact with skin oil or mud. Thankfully, there are organizations such as the Ozark Highlands Grotto (a grotto is a caving group) that are working to uninvasively restore the damage to the caves; this ensures that they avoid all cleaning chemicals that could contaminate cave water or harm cave organisms. They remove garbage and clean graffiti from walls, but sometimes recent calcite deposits seal the graffiti into the cave permanently. Cave resoration must also consider which paintings/graffiti on caves to remove: some are pre-historic pictographs or petrographs.

Cave resoration teams have also resorted to gating caves closed to prevent human entry. Still, they are constructed to allow the passing of bats and other animals in and out of the cave so the ecosystem balance isn’t disrupted.

(Image from Wikimedia Commons; “Skeleton Cave near Bend, Oregon”   https://commons.wikimedia.org/wiki/File:Skeleton_Cave_near_Bend,_Oregon.jpg)

Cave Life

Energy Sources

Information from (Culver, David C., and Tanja Pipan).

Because caves are entirely or almost entirely lacking in light, photosynthesis is not a viable method for primary energy production. Instead, many caves rely on chemoautotrophy as their base energy source which draws the required energy from inorganic chemical bonds (chemoautotrophs are also found in other extreme environments like deep sea vents). In caves, the energy is commonly derived from H2S, or hydrogen sulfide. The chemical reaction is as follows: H2S + 2O2 -> SO4 2- + 2H+ with an energy output of 798.2 kj/mol. This energy is then converted into ATP, the unit of energy for cell metabolism.

Chemoautotrophy is believed to be one of the oldest forms of energy production, present in the early stages of Earth’s formation. The reliance on chemoautotrophy instead of other sources of organic carbon, such as bat guano left in a cave, is evidenced by the comparison of the 14N and 13C isotope ratios for ecosystems that rely on chemosutotrophy vs. energy derived from organic carbon. The analysis of each’s distinct and distinguishable ratio can determine the primary source of energy in a particular ecosystem. Heavy reliance on chemoautotrophy is found largely in the deep regions of the cave.

Apart from chemoautotrophy, organic carbon sources can enter the cave through the surface opening or via displacement from the surface; the transfer of energy from one system to another is called a spacial subsidy. Means of transport include flowing water that carries particulate matter through a cave stream and percolating water that brings dissolved matter and microscopic bacteria through the bedrock. Furthermore, some animals spend parts of their lives inside the caves, but still rely on the surface environment; these are called Trogloxenes. An examplpe of a trogloxene is the endangered Grey Bat, which hibernates and sleeps during the day in Missouri caves. Such animals are crucial to cave life survival because they transfer energy from the surface to the cave. They could deposit energy in their droppings (for example, bat guano), their eggs, or their foresaken corpses. Some cave species are adapted to harvest energy from penetrating tree roots as well.

Due to the extremely limited nature of energy available for cave life, species diversity is severely diminished compared to that on the surface; outside, there are many kinds of flowers, for example, so many different kinds of pollinators can survive mutually.

(Image from Wikimedia Commons; “Hibernating bats” https://commons.wikimedia.org/wiki/File:Hibernating_bats_(5600306079).jpg)

Fish (Amblyopsidae family)

In a cave, food sources are scarce. Due to this scarcity, the cave fish have diverse diets. They eat plankton, small invertebrates (such as crayfish), cave crickets, salamander larvae, amphipods and isopods, their own young, bacteria, fungi, aquatic insect larvae, and decaying organisms (Fish of Ozark Caves: Missouri department of Conservation).

Pollution of surface water due to human sewage disposal, agricultural waste disposal, and heavy silt deposition has threatened cave fish populations. The pollution enters the groundwater system through sinholes or by percolation through the soils and cracks in the limestone or dolostone bedrock (Fish of Ozark Caves: Missouri department of Conservation). Understanding groundwater flow patterns and potential routes for cave water contamination can guide us in developing effective methods for the rehabilitation of our cave fish populations. One effective method of filtering herbicides and pesticides from groundwater sources is to plant “a buffer of trees and other plants around sinkholes,” (“Grotto Sculpin”). The cave fish populations are also threatened by habitat destruciton and over-collection (Slay, Michael E., et al.).

Spring Cavefish (Forbessichthys agassizi)

The Spring Cavefish is the only Amblyopsidae fish inhabiting Missouri caves that has pigment and eyes (though they are very small and can only distinguish between light and dark). It is yellow-brown with a yellow belly and can have a thin yellow stripe along the side. It also has a single dorsal fin that lacks spines, a rounded tail, and is about 2-3 in long. Its “head and body have numerous rows of sensory papillae” (“Spring Cavefish”) that serve as the taste buds for the fish; it primarily uses taste when searching for food, and it eats aquatic crustaceans. The Spring Cavefish spends the night outside in surface waters and the day underground in caves, thus it is an intermediate species between “obligate cave dwelling fish” and surface fish. Sadly, this fish is listed as State Endangered in Missouri due to its small population and limited range (“Spring Cavefish”).

The other five types of cave-dwelling Amblyopsidae fish are adapted to cave life (stygobionts) and have progressively increasing levels of eye and pigment degeneration. Hybridization between the epigean (surface-swelling) and troglomorphic (cave-dwelling) species of fish can produce combinations and different degrees of pigment reduction and eye degeneration. Sometimes, it can lead to interesting combinations such as the complete absence of pigmentation but with functional eyes (Romero, Aldemaro). Three species of stygobiontic Amblyopsidae fish are found in Missouri caves: Typhlichthys subterraneus (Southern Cavefish), Typhlichthys eigenanni (Eigenmann’s Cavefish), and Troglichthys rosae (Ozark Cavefish) (“Southern Cavefish”).

It is believed that the degree of eye degeneration can be correlated with the length of time the population spent in complete darkness (Culver, David C., and Tanja Pipan). However, there is much controversy over the evolutionary mechanisms that have led to the observed eye degeneracy, especially since the populations are so isolated yet they display convergent evolution (independently evolving to display similar phenotypic traits). One theory is based on phenotypic plasticity and the inference that troglomorphic species were derived from epigean species via natural selection of phenotypic plasticity. Phenotypic plasticity means that one geneotype can produce multiple phenotypes when exposed to different evironments (for example, light vs. dark). In a study by Romero and Green (2005), the larvae of epigeans, stygobionts, and hybrids were placed under lighted and dark conditions. Analysis discovered that the epigean species raised in darkness had underdeveloped eyes, and the troglomorphic species had somewhat developed eyes. Thus, both the surface and cave populations retained similar genotypes (genetic compositions), which allowed for their adaptation to the environmental conditions (Romero, Aldemaro). Another theory is based on the assumption that eye development is dependent on many independent genes, and that neutral mutations in any of them can lead to eye degeneracy. This also describes possible mechanisms of lens apoptosis (cell suicide), where the mutation of one of a number of genes causes apoptosis and regression of the eye into the orbit socket. This theory successfully accounts for the convergent evolution patterns seen in fish and other cave-dwelling species (Culver, David C., and Tanja Pipan). Further research is being conducted in order to better understand the mechanisms responsible for the loss or reduction of certain phenotypic traits. These projects are also taking advantage of the fact that the cave populations tend to be small and isolated; thus, they can be considered individually from an ecological standpoint and used as separate experiments (Romero, Aldemaro).

(Image from Wikimedia Commons; “Astyanax fasciatus (Mexican Blind Cavefish)” https://commons.wikimedia.org/wiki/File:Astyanax_fasciatus_(Mexican_blind_cavefish)_1_(15719439215).jpg)

Other adaptations to cave life and complete darkness are controled by natural selection. They include an increased olfactory lobe in the brain (controls hearing) and a decreased optic lobe of brain (controls sight). To compensate for the loss of their eyes, these fish have abundant papillae and sensory nerves on their head and sides that allow them to detect motion in the water “from prey, conspecifics, their surroundings, and potential dangers,” (Slay, Michael E., et al.). When looking for food, the cave fish will run their head along the ground surfaces in order to locate food with its sensors. The fish also have an enhanced sense of odor to aid in food detection. Furthermore, the troglomorphic fish have larger heads which displace more water and allow for easier detection of obstacles. The smaller gas or swim bladders might be prefered because the cave waters tend to be shallow and thus the gas bladders serve no purpose (Romero, Aldemaro). Enlongated fins promote smooth swimming patterns–perhaps erratic escape motions are not necessary in the cave environment with few predators. In addition, constant, cool temperatures and steady dissolved oxygen levels help the fish maintain lower metabolic rates, require less food, and live longer lives (it is thought that these fish live to be older than 10 years). These decreased metabolic rates conserve energy in the limited resource environments within caves (the fish are predators, so they rely on other species for energy which may not be readily available). Similarly, the cave fish species display less frequent mating and lay fewer yet larger eggs (Culver, David C., and Tanja Pipan); for example, one Southern Cavefish female may only lay 50 eggs (“Typhlichthys Subterraneus”) When water levels rise in the caves each spring and encourage the fish to mate, only about 20% of mature females will spawn (“Ozark Cavefish”). The females will carry her eggs in her gill chamber for 4-5 months until the babies hatch. Even though there is a larger reproductive effort, these behaviors allow the fish to wait for periods of high carbon availability to breed, while save energy during starvation periods (Culver, David C., and Tanja Pipan).

Southern Cavefish (Typhlichthys subterraneus)

The Southern Cavefish appears whitish-pink (due to the blood vessels beneath the skin) and scaleless (although there are small scales present), and it has no eyes. Furthermore, its head is flattened and enlongated. Its fins and tail are rounded, though it lacks a pelvic fin. Its anus is also very far forward. It grows to be 1.5-3.5 in long. The Southern Cavefish can be found in caves of the central and southeastern Ozarks (“Southern Cavefish”).

Ozark Cavefish (Troglichthys rosae)

The Ozark Cavefish is nearly indistinguishable from the Southern Cavefish; however their ranges do not overlap. The Ozark Cavefish is found “in 32 caves of the Springfield Plateau in the southwestern Ozarks,” (Slay, Michael E., et al.). This species prefers quiet pools at shallow depths beneath the ground surface (Slay, Michael E., et al.)The Ozark Cavefish is pigmentless and eyeless and its lower jaw protrudes farther than its upper. It has rounded fins and tail. It grows to be 2.25 in long. This species is critically endangered (“Ozark Cavefish”).

Eigenmann’s Cavefish (Typhlichthys eigenmanni)

Recently declared a separate species from the Southern Cavefish, the Eigenmann’s Cavfish is very similar. It is also found in the Salem Plateau in the south-central Ozarks (within the Southern Cavefish’s range). The two species are distinct genetically, however. This species is pigmentless, lacks eyes, and contains the sensory paillae to aid in the detection of its surroundings. The Eigenmann’s Cavefish inhabits mostly caves at or near the water table, and it is found in similar habitats as the Ozark Cavefish (Slay, Michael E., et al.).

Banded Sculpin (Cottus carolinae)and Grotto Sculpin (Cottus specus)

Sculpins are found clinging to the bottom of a stream with cold, turbulent water. They might take shelter under rocks on the stream bed, as well. Interestingly, they will seldom venture more than 100 yards along the stream for their entire lives. As bottom dwellers, they have evolved streamlined bodies to help them maintain their position in the current. In general, they have large heads, flattened bodies that taper to their tails, and enlongated pectoral fins. They also have very large mouths that allow them to swallow food alost as big as themselves, including small fish, snails, crayfish, and immature aquatic insects. They hunt at night and ambush their prey. Sculpins can also modify their coloration in order to blend into the background more effectively. They lack scales completely, but the scales are replaced by small prickles around their body (“Banded Sculpin”).

Sculpins live to be about 6 years old. In the spring, the sculpins mate; this includes the males digging cavities in the stream bed under rocks and logs. The males will also guard the approximately 200 eggs until they hatch (“Banded Sculpin”).

The Banded Sculpin is reddish-brown and has darker vertical bands along its sides, including one well-defined, black band at the base of its tail. It is 2.5-5 in long (“Banded Sculpin”).

(Image from Wikimdia Commons; “Banded sculpin” https://commons.wikimedia.org/wiki/File:Banded_sculpin.jpg)

The Grotto Sculpin is very similar to the Banded Sculpin, but the overall coloration is paler; they are light tan. This species is only found in one Missouri location, and is hence federally endangered (“Grotto Sculpin”).

Bats

Bats are an important member of the Missouri cave ecosystems as they are a key provider of energy in their guano and help to maintain food chain balances outside the caves and around their entrances as they feed on huge numbers of insects, pollinate plants, and distribute seeds (Adler, Seth). The bats hunt at night and feed on moths, mosquitoes, and other small insects. They must hunt at night because of the cover of darkness necessary to avoid predation from hawks and owls. Despite the darkness, the bats are able to hunt at night because of their ability to ecolocate, sending out untrasound cries that bounce off objects and back to their ears as echos.

Some bats use caves yearlong as both shelters for hibernation in the winter and for maternity colonies (where the females raise their young) in the summer. These species include the endangered Gray Bat and the very common Tri-Colored Bat. During the summer months, the caves are important because they provide secluded day roosts to hide from predators. Other bats use caves only as hibernacula during the winter. These species include the Big Brown Bat, LIttle Brown Myotis, Indiana Myotis, and Northern Long-Eared Myotis (Slay, Michael E., et al.).

Sadly, the Ozark bat populations are declining quickly due to human disturbance of their cave ecosystems and use of pesticides that poison the insects the bats feed on. Furthermore, the “white-nose syndrome” has spread around the globe (as humans have enabled global transportation and travel) and severely damaged the ability of the bats to survive. The fungus also travels profusely from bat to bat, owing to the bats’ community-based behavior to roost in very close quarters. White nose syndrome is a white fungus that grows on the skin of the bat and causes relentless irritation and discomfort, so much so that the bats wake from hibernation. Awoken, they must search for food, of which there is none in the winter months, and water; the bats helplessly expend their stored up energy that was supposed to last through winter trying to find food and will eventually die of starvation (Kolbert, Elizabeth).

For a complete research report on remnant bat populations that survived the fungus and their physiological and behavioral changes or differences that may have contributed to their survival or resulted from their immunological recovery click here.

Citation: Lilley, Thomas Mikael, et al. “White-Nose Syndrome Survivors Do Not Exhibit Frequent Arousals Associated with Pseudogymnoascus Destructans Infection.” Frontiers in Zoology, 3 Mar. 2016. Creative Commons Lisence link: http://creativecommons.org/licenses/by/4.0/. No changes made.

Gray Myotis (Gray Bat) Myotis grisescens

The Gray Bat is the largest myotis bat and can be identified by its distinctive uniform gray coat. Its ears and wings are grey to black.  Also unique to htis species is wing membranes that attach to the ankle and not the toes. For hibernation, they form colonies of up to 250,000 bats and typically hibernate in caves that trap cold air. In contrast, maternity colonies prefer warmer caves and smaller groups of only about 30,000 bats. The Gray Myotis is 3 in long with a 10-12 in wingspan (“Gray Myotis (Gray Bat)”).

Tri-Colored Bat (Perimyotis subflavus)

The Tri-Colored Bat is very small and common in the Ozark region. Its distinguishing traits include its pink forrearms and tri-colored fur: it has a red base, a yellow middle, and a brown tip. It is 3-3.5 in long with a 1.25-1.75 in long tail (“Tri-Colored Bat”). Also, this species has slow and erratic flight patterns. For hibernation, these bats return to the same place anually and hibernate in small groups. They hibernate in the warmest and most humid parts of the caves. The female maternity colonies are made up of only about 20 bats and the males roost alone during the summer. Sadly, the endangered Ozark Big-Eared Bat is no longer found in Missouri caves because of human interference or destruction of cave habitats (Slay, Michael E., et al.).

Big Brown Bat (Eptesicus fuscus)

Other bats use caves primarily as protection during hibernation. One is called the Big Brown Bat, and it is a comparatively large bat in Missouri. They can be found in very cold caves, including man-made structures; this improves how they fare with modern human development of cave ecosystems. They have no tail and their fur is brown–lighter ventral (belly) fur than dorsal (back) fur. (Slay, Michael E., et al.)

Little Brown Myotis (Little Brown Bat) Myotis lucifugus

The Little Brown Myotis (Little Brown Bat) has dark glossy brown fur on its back and it has a metallic, yellow-brown appearance. Its ears are long, narrow, and blunted at the tip. Its wings, tails, and ears are glossy dark brown. A distinguishing feature is its hairs that extend to its toes. It is 3-3.75 in long with a 1.25-1.75 in long tail. Also, this species only eats adult flying insects (“Little Brown Myotis (Little Brown Bat)”). The Little Brown Bat is often found hibernating with the Indiana Bat and is very widespread. (Slay, Michael E., et al.)

Indiana Myotis (Indiana Bat) Myotis sodalis

Similar to the Little Brown Bat, the Indiana Bat also primarily uses caves for winter hibernation. They are often found clumped and huddling together for warmth and will move together in the caves, responding to the temperature changes. They prefer cool caves with humidities of 65-95%. This bat has brown-gray dorsal fur and lighter brown ventral fur with pink-tinted lips. Their wings and ears are black-brown. This species is 2 in long with an 8 in wingspan. To distinguish this bat from other myotises, look for a distinct keel on its calcar. (A calcar is a supporting extension of cartilage on the bats’ inner ankle that helps to spread its wing membrane between its tail and rear legs). Furthermore, their wing membranes attach on their foot down to the end of their toes. Unfortunately, their population is heavily affected by the white nose syndrome (“Indiana Myotis (Indiana Bat)”).

Northern Long-Eared Myotis (Northern Long-Eared Bat) Myotis septentrionalis

Lasly, the Northern Long-Eared Bat is a medium sized bat with medium-dark brown fur on its back and a little fighter brown fur on its front. Distinguishing it from other myotises is its long ears. It tends to hibernate individually in crevices or cracks of caves; often only its nose and ears are visible. The Northern Long-Eared Bat population is federally listed as threatened, primarily due to the White-Nose Syndrome (“Northern Long-Eared Bat”).

For more bats of Missouri, click here.

Salamanders

Salamanders are also found in caves, both as stygobiotic (live only in groundwater systems) and non-stygobiotic species. Both play important roles as predators in their regions. Many species live in the deep cavities and phreatic waters (groundwaters) of caves, making them only accessible to humans via wells (Culver, David C., and Tanja Pipan), and typically, their populations are low and restricted to small areas (Romero, Aldemaro). They are found both in the transition zones (minimal light) and dark zones (no light) of caves (Slay, Michael E., et al.).

Much like other cave vertebrates, they are slow to mature (females reach reproductive maturity in 11-14 years and males do in 15-18 years) (Romero, Aldemaro). The many cave salamander species whose larvae attain reproductive maturity are believed to conserve energy by bypassing complete development and retaining such larval features as external gills (this characteristic is known as neoteny). Furthermore, many salamander species in caves will hybridize (Culver, David C., and Tanja Pipan).

Cave salamanders have chemo- and mechanoreceptors that help them detect food in streams or members of the same species. Their diet includes aquatic invertebrates and anthropods, other salamanders, and bat guano. They are hunted by larger fish, mammals, birds, and reptiles (Romero, Aldemaro).

Cave Salamander (Eurycea lucifuga)

The Ozark Cave Salamander is brightly colored and yellow-oragne or reddish-orange with many irregularly-shaped black spots. A distinguishing feature is its very long tail with a frequently black tip. Cave Salamanders breed in caves and the females lay eggs in cave streams, rimstone pools, or surface springs or rocky streams. It is 4-6 in long and has 13-14 costal grooves (“Cave Salamander”). (Costal grooves are grooves on the interior side of the ribs and that accomodates the arteries and nerves (“Coastal Grove.”).) The larvae are dark with gills and metamorphose in 1-2 years (Romero, Aldemaro). As adults, the salamanders move to the caves and undergo eye and pigment reduction (Culver, David C., and Tanja Pipan).

Dark-Sided Salamander Eurycea longicauda melanopleura and Long-Tailed Salamander Eurycea longicauda longicauda

These species are subspecies of Long-tailed salamanders. They require aquatic habitats for breeding and larval development then move to terrestrial landscapes for adulthood. This has subject their population to harm from clearcutting and acid drainage (Ryan, Travis J., and Christopher Conner). The Dark-Sided Salamander look similar to the Cave Salamander but are darker on their sides and are yellow-green or yellow-brown (Slay, Michael E., et al.). Their sides are also populated with white spots (“Long-Tailed Salamander”).

The Long-Tailed Salamander is more yellow than the Dark-Sided Salamander and has “a distinct dark chevron pattern on the sides of its tail,” (Slay, Michael E., et al.). The two species will hybridize which produces varying color schemes. It is also interesting that this species does mature all the way to developmental completion (does not display neoteny). Furthermore, both long-tailed species migrated in and out of caves, spending the winter months in the sheltered areas (Ryan, Travis J., and Christopher Conner). They are 4-6.25 in long with 13-14 costal grooves (“Long-Tailed Salamander”).

To escape from predators, these species raise their tails, distracting the attention from their head to their tail which can twist off and regrow easily. They might also use their tail to jump quickly out of harms way (“Long-Tailed Salamander”).

Western Slimy Salamander Plethodon albagula

Western Slimy Salamanders are darkly colored and have white or silver spots on their sides. Their tail is thick and rounded. It is 4.75 – 6.75 in long and has 16 costal grooves. As its name suggests, “this species secretes a thick, very sticky substance that adheres to skin like glue. It causes dust, dirt or bits of dead leaves to stick to one’s hands and is difficult to remove,” (“Western Slimy Salamander plethodon albagula”). Unlike other cave species, this salamander lives in caves during the summer months that are more dry and will emerge only after heavy rains. In the winter they are often found under rotting logs. Furthermore, the females lay their eggs in the caves (they suspend them from crevices) and remain with them until they hatch. As does the entire Plethodon genus, the hatchlings do not have a larval stage, but develop completely within the eggs (“Western Slimy Salamander plethodon albagula”).

Ozark Zigzag Salamander Plethodon andusticlavius

The Ozark Zigzag salamander can be found in the Ozarks of southwestern Missouri. It is small (2.25-4 in long) and colored dark brown-gray with white speckles on its sides and a yellow or orange band along its back and has irregular, lobed, or wavy edges, hence its name (Slay, Michael E., et al.). The stripe is narrow but the widest part is at its hind legs. Its belly is mottled white and black. There are 17-19 costal grooves (“Ozark Zigzag Salamander”).

Southern Red-Backed Salamander Plethodon serratus

Although similar to the Ozark Zigzag Salamander, the Southern Red-Backed Salamander is primarily found north and east of its range. The Southern Red-Backed Salamander prefers warmer and drier habitats that does the Ozark Zigzag Salamander. Furthermore, while it too has a orange-red stripe along its back, the Southern Red-Back Salamander’s stripe is more uniformly serrated (serrations correspond with costal grooves) and has an even width down the entire body. Its sides are dark brown-gray and its belly is mottled gray. This species is 2.25 – 4 in long and has 18-19 costal grooves (“Southern Red-Backed Salamander”).

Grotto Salamander (Ozark Blind Salamander) Eurycea spelaea

This is the only troglobiotic salamander in the Ozarks. This means that is is evolutionarily adapted to cave life. Their larvae are gilled, have a rounded snout, and are found in cave streams or springs outside of the caves. In 2-3 years, the larvae metamorphose and return to the caves. Adults require complete darkness and streams running through the caves (“Grotto Salamander Eurycea spelaea”). The adults are pale or pinkish-white. They have long rounded tails and degenerate eyes that are covered by partially fused eyelids. The larvae posess more gray color, functional eyes, and can have gray spots on their sides. When they reach sexual maturity, the males have “a swollen upper lip, a pair of cirri extending from the upper lip [(these are hairlike filiments that have extremely sensitive vibration sensors used to locate food)], and a mental gland on hte chin which is used for courtship (Slay, Michael E., et al.). They are 3 – 4.75 in long with 16-19 costal grooves. These salamanders are at the top of the cave food system and eat flies, bettles, worms, and other aquatic or terrestrial invertebrates. Their larvae eat bat guano, and consequently, their populations are largest in caves with bat populations (Slay, Michael E., et al.).

Currently, their population is widespread and not threatened, but the groundwater contamination and water table depletion will leave them vulnerable (Slay, Michael E., et al.).

The Olm lays an egg!

As a general cave enthusiast, it was exciting news to hear that a Slovenian olm had laid an egg in Postojna Cave. The olm is a very endangered species, especially since breeding is extremely rare (one egg is laid every 6 or 7 years!). I was able to personally visit Postojna Cave Park and observe the olms in their aquarium. I invite you to read more about the olm and the new eggs here!

Citation: Gonzaga, Shireen. “Rare Salamander Lays Eggs in Slovenia Cave.” EarthSky, EarthSky Communications Inc., 11 Feb. 2016, earthsky.org/earth/rare-salamander-lays-eggs-in-slovenia-cave.

(Image from Wikimedia Commons “Olm (Proteus anguinus) in Moulis, Ariege (Laboratoire souterraine, CNRS)” https://commons.wikimedia.org/wiki/File:Olm_(Proteus_anguinus)_in_Moulis,_Ariege_(Laboratoire_souterraine,_CNR

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