Milyeringa brooksiBrooks' cavefish

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Geographic Range

Known only from the caves and wells of the Cape Range National Park in the North West Cape (Cape Range Peninsula) of Australia. The habitat of this species is exclusively karst spanning roughly 50 kilometers of subterranean habitat. (Chakrabarty, 2010)

This species is found in the karst systems and underground water channels from Tulki Well (22° 06’S. 113° 54’E) in the north, to an area near the abandoned Ningaloo tower (22° 42’S 113° 40’E; also called Point Cloates Lighthouse on local maps) in the southwestern portion of the Cape Range of Australia. The type locality is Pilgonaman Well, which along with Tulki Well is located within Cape Range National Park.The distribution of these fishes spans approximately 75km along Yardie Creek road on the southeastern side of the North West Cape. The range likely spans underground interconnected waterways that incorporate these surface openings (wells and caves) separated from those belonging to Milyeringa veritas in the northern portion of the North West Cape. (Chakrabarty, 2010)

Habitat

Although individuals can be found at or near the surface, most individuals are presumably in groundwater aquifers of unknown depth. (Chakrabarty, 2010)

  • Other Habitat Features
  • caves

Physical Description

Individuals are small (less than 40 mm SL), unpigmented, eyeless stygobitic fish. The head is large (about 40% of body length not including caudal fin), broad (area posterior to cheeks is the widest part of the animal) and has a nearly flat dorsal surface. The eyes are absent, with no remnants of a lens or other features related to vision. The mouth is large (about 45% of the head length). The lower jaw protrudes slightly anterior to upper jaw. The nostril are oval and somewhat tube shaped. The tongue is flat and blunt. The teeth are small, unicuspid, and strongly recurved (i.e., facing into the mouth) and set in three to five irregular rows. The gill cover is large (about 40% of the head length). The gill rakers are long and thin, and there are small denticles present on the medial side. The gill filaments are thick and short (about the same length as the longest rakers). One line of sensory papillae loosely follows shape of anterior edge of opercle and preopercle; the opercular row of papillae continues on the ventral side of head around the gular region. Four parallel rows of sensory papillae are present on the cheek. The largest papillae on the head are present around the lips. The sensory papillae on the body are less conspicuous than those on head. There is no lateral line. There are ten to 12 vertical lines of papillae present on the body. In some individuals papillae are more conspicuous on one side of body than the other. The body is slim relative to the head becoming thinner and shorter posteriorly. There are twenty-four total vertebra. The body is covered in thin, deeply embedded, transparent cycloid scales. There are two separate dorsal fins: the first is short (less than 1/3 of height of the second) with four thin and weak spines, the second has nine unbranched but segmented rays. There are four rays in the pelvic fin, nine in the anal fin. There are 18 segmented unbranched principal caudal-fin rays and 14 pectoral-fin rays. The second dorsal, pectoral, pelvic, anal, and caudal fins all have elongated trailing rays to varying degrees.

In life, this species is depigmented, appearing almost uniformly pinkish white. The pink color is most conspicuous where blood is concentrated, such as over the gills as seen through the gill cover. The area above the brain is transparent and the brain case appears purplish in life. The fins and gill covers are hyaline.

For more information see the description by Chakrabarty (2010) from which this account is based. (Chakrabarty, 2010)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    40 (high) mm
    1.57 (high) in

Development

Developmental biology is unknown. Larval individuals and reproduction have not been observed. (Chakrabarty, 2010)

Reproduction

There is nothing known about mating systems in this species. (Chakrabarty, 2010)

Nothing is known about reproduction in this species. (Chakrabarty, 2010)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • oviparous

Nothing is known about parental investment in this species. Like other, similar fish, it is likely that females invest in nutrients for eggs and that there is no further parental investment.

Lifespan/Longevity

Lifespan is unknown. Individuals have never been kept in captivity and wild longevity has not been documented. (Chakrabarty, 2010)

Behavior

Although blind individuals are still sensitive to movement in the water. Sensory papillae adorning the body are likely used to sense prey. Having evolved without predators these animals have no "flee" response and can be picked up rather easily by hand or using a small net. These blind cave fish show no sensitivity to light. Individuals were not observed interacting but are sometimes seen in small groups. (Chakrabarty, 2010)

Home Range

Home range sizes of individuals are unknown.

Communication and Perception

Communication is unknown although tactile communication appears to be the only viable option given that individuals do not see or produce sounds. Chemosensory communication may be a possibility but no morphological clues to the production of pheromones or their reception have been discovered. (Chakrabarty, 2010)

Food Habits

These fishes have been found with small invertebrate parts in their guts but these could not be identified with much confidence. It is not known if these were obtained from predation of live animals or from salvaging, such as from ingesting detritus. (Chakrabarty, 2010)

Predation

There are no known predators. It is presumed that as a blind-cave fish that this species evolved successfully in a subterranean environment without predators. (Chakrabarty, 2010)

Ecosystem Roles

This species is found alongside a blind synbranchid eel, Ophisternon candidum, and a crustacean, Stygiocaris lancifera. Although small invertebrates, mostly insects, are sometimes observed in the wells and caves with these fishes it remains unknown how these organisms interact with one another. (Chakrabarty, 2010)

Economic Importance for Humans: Positive

There is no role for these animals in the economy. Few individuals know of their existence, although in the future they may be used to generate interest in the region among tourists and other visitors to the North West Cape. (Chakrabarty, 2010)

Economic Importance for Humans: Negative

The limited water available to the few thousand Australians living in this region may put a demand on the subterranean aquifers that are the only habitat of these fishes. (Chakrabarty, 2010)

Conservation Status

Not currently listed in any conservation list. However, as noted by (2010), "The endangered status of Milyeringa veritas under the Western Australia Conservation Act should be expanded to include the new species. It is vital that these rare and poorly-studied species be managed and protected." (Chakrabarty, 2010)

Contributors

Prosanta Chakrabarty (author), Louisiana State University.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

chemical

uses smells or other chemicals to communicate

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

vibrations

movements of a hard surface that are produced by animals as signals to others

References

Chakrabarty, P. 2010. Status of Milyeringidae, with the description of a new blind cave fish from Australia, Milyeringa brooksi, n. sp.. Zootaxa, 2557: 19-28. Accessed June 04, 2011 at www.mapress.com/zootaxa/2010/f/z02557p028f.pdf.