''Myotis vivesi'', the fish-eating bat or fish-eating myotis, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most ...

that lives around the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

, and feeds on

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

and

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s. It is the largest species of the genus ''

Myotis The mouse-eared bats or myotises are a diverse and widespread genus (''Myotis'') of bats within the family Vespertilionidae. The noun "''myotis''" itself is a New Latin construction, from the Greek "''muós'' (meaning "mouse") and "''oûs''" (me ...

'' in the Americas, and has exceptionally large feet, which it uses in hunting. It was described in 1901 by Auguste Ménégaux. It was previously considered the only member of the ''Myotis'' subgenus ''

Pizonyx The mouse-eared bats or myotises are a diverse and widespread genus (''Myotis'') of bats within the family Vespertilionidae. The noun "''myotis''" itself is a New Latin construction, from the Greek "''muós'' (meaning "mouse") and "''oûs''" (me ...

'', but ''Pizonyx'' is now considered to contain all American ''Myotis'' species, along with two Eurasian ones.

Description

''Myotis vivesi'' is the largest species in the genus ''

'' in the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

, and is similar in size to the

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

n '' Myotis myotis'' (greater mouse-eared bat). The

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

averages in length. The second largest ''Myotis'' species in the New World, ''

Myotis velifer The cave myotis (''Myotis velifer'') is a species of vesper bat (''Vespertilionidae'') in the genus '' Myotis''. Description It is larger than most other bats in the ''Myotis'' group, with a forearm of . The bat is brown with short ears, and ca ...

'', has a skull long, and feet long; ''M. vivesi'' has greatly elongated hind feet, which average long. In common with other fish-eating bats, ''Myotis vivesi'' has long, efficient wings, with high aspect ratio and low

wing loading In aerodynamics, wing loading is the total mass of an aircraft or flying animal divided by the area of its wing. The stalling speed of an aircraft in straight, level flight is partly determined by its wing loading. An aircraft or animal with a ...

, and large feet with sharp claws. The

uropatagium The patagium (plural: patagia) is a membranous body part that assists an animal in obtaining lift when gliding or flight. The structure is found in extant and extinct groups of flying and gliding animals including bats, birds, some dromaeosau ...

(the wing surface between the hind legs) bears a fringe of silky hairs of unknown function; the uropatagium itself is used in hunting. The

fur Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily guard hair on top and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an insulating blanket t ...

is around long, and varies in colour from fawn to brown, with the base of each hair being dark grey. In common with other piscivorous species of ''Myotis'', the underside of ''M. vivesi'' is pale.

Distribution

''Myotis vivesi'' is found along the coast of the

in the Mexican states of Sonora,

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

and Baja California Sur, mostly on small islands. A small population exists on the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

coast of the Baja California peninsula, between

Isla Encantada Isla Encantada is an island in the Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marg ...

and Punta Coyote. Since it lives on small islands, the

range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

of ''M. vivesi'' is naturally fragmented, but data from

microsatellites A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organism's genome. ...

and the

mtDNA control region The mtDNA control region is an area of the mitochondrial genome which is non-coding DNA. This region controls RNA and DNA synthesis. It is the most polymorphic region of the human mtDNA genome, with polymorphism concentrated in hypervariab ...

indicate that there is no isolation by distance in the species.

Ecology and behaviour

''Myotis vivesi'' feeds chiefly on marine

s, including the

squat lobster Squat lobsters are dorsoventrally flattened crustaceans with long tails held curled beneath the cephalothorax. They are found in the two superfamilies Galatheoidea and Chirostyloidea, which form part of the decapod infraorder Anomura, alongsi ...

Pleuroncodes planipes ''Pleuroncodes planipes'', sometimes called the pelagic red crab (or simply " red crab"), tuna crab or ', is a species of squat lobster from the eastern Pacific Ocean. Description ''Pleuroncodes planipes'' is a bright red animal, up to long. It ...

''. Only one other bat species, '' Noctilio leporinus'', hunts in marine waters. The guano produced by ''M. vivesi'' is red if it has eaten crustaceans, and black if it has eaten fish; green guano and brown guano result from feeding on algae and insects, respectively. As well as fish and crustaceans, ''M. vivesi'' also feeds occasionally on aerial

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

s. ''M. vivesi'' can cover large distances when hunting; in 1970, scientists saw "a group of about 400 ''M. vivesi'' around a boat at least 7 km .3 milesfrom the shore". ''M. vivesi'' inhabits an arid environment and has evolved the ability to concentrate its

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular ...

; this allows it to survive by drinking

seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appr ...

. ''M. vivesi'' prefers to roost either in

cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

s or under rocks revealed by landslides. They sometimes share their roosts with least petrels (''Halocyptena microsoma'') and black petrels (''Oceanodroma melania''). On many islands in the

where these petrels nest, the

western whiptail The western whiptail (''Aspidoscelis tigris'') is a species of lizard in the family Teiidae. The species ranges throughout most of the southwestern United States and northern Mexico. Most of its populations appear stable, and it is not listed as ...

is a known predator of their eggs and chicks, and the petrels generally show only fearful responses towards the lizards and capable of doing only little to defend their offspring. However ''M. vivesi'' that share roosts with these petrels swiftly react by biting and flapping when the lizards are detected, effectively warding the reptiles off. This may be an example of a

symbiotic relationship Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

in which the bats help defend the young of nesting petrels, increasing the chances of survival for petrel chicks.

Taxonomy and evolution

''Myotis vivesi'' was first described by Auguste Ménégaux in 1901. The species was moved to a new genus, ''Pizonyx'' by Gerrit Smith Miller Jr. in 1906, but that taxon is now usually included in ''

''. Ménégaux gave no indication of the

etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...

of the specific name ''vivesi''; it may either refer to a person called Vives, or derive from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

verb '' vivere'', "to live". If Vives was a person, he was not the collector of the specimens, that being recorded as Léon Diguet. No subspecies of ''M. vivesi'' have been recognised. The closest relatives of ''M. vivesi'' are other New World species of ''Myotis'' which are not adapted to piscivory, rather than the other piscivorous bats in the genus. This indicates that the adaptations to catching fish in ''M. vivesi'' and other species are the result of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

. No fossils attributable to ''M. vivesi'' have been discovered. A fossil species of ''Pizonyx'', ''Pizonyx wheeleri'', was named by Walter Dalquest and Daniel Patrick in 1993 from the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

of Texas, but according to a 1993 review by Nicholas Czaplewski, this species instead belongs to the genus '' Antrozous'' and may not even be distinct from the living species '' Antrozous pallidus''.

References

{{Taxonbar, from=Q2206910 Mouse-eared bats Fauna of the Baja California Peninsula Marine mammals Endemic mammals of Mexico Endangered biota of Mexico Mammals described in 1901 Taxonomy articles created by Polbot Fauna of the Sonoran Desert Fauna of Gulf of California islands