The Aeglidae are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s currently restricted to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. They are the only

anomura Anomura (sometimes Anomala) is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans include the word ''crab'', all true crabs are in the sister group to the Anomura, the Brachyura (the two groups ...

ns to be found in fresh water except for a single

hermit crab Hermit crabs are anomuran Decapoda, decapod crustaceans of the superfamily (taxonomy), superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit c ...

species, '' Clibanarius fonticola'', on

Espiritu Santo Espiritu Santo (, ; ) is the largest island in the nation of Vanuatu, with an area of and a population of around 40,000 according to the 2009 census. Geography The island belongs to the archipelago of the New Hebrides in the Pacific region ...

Vanuatu Vanuatu ( or ; ), officially the Republic of Vanuatu (; ), is an island country in Melanesia located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of northern Australia, northeast of New Caledonia, east o ...

. They live between 20° S and 50° S, at altitudes between .

Description

Aeglids resemble

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, alongs ...

s in that the

abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

is partly tucked under the

thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

. The notable

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

in the abdomen is related to the behaviour of carrying fertilised eggs on the

pleopod The anatomy of a decapod consists of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment – often called a somite – may possess one pair of appendages, although in various groups these m ...

s. The

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

length of the largest species may approach , but most are considerably smaller. Aeglids are

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

, preferring plant matter, but also eating adult

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

and fly

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e. The internal anatomy has been described for ''Aegla cholchol'' and generally resembles that of other anomurans, particularly galatheoid squat lobsters. The

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

of the antennal gland bladder differs from that in other anomurans in having a twisted tubular structure which was interpreted as an adaption to the freshwater lifestyle.

Life cycle

Mating is preceded by a period of

courtship Courtship is the period wherein some couples get to know each other prior to a possible marriage or committed romantic, ''de facto'' relationship. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marri ...

, and does not coincide with

moulting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...

, as it does in many other

decapods The Decapoda or decapods, from Ancient Greek δεκάς (''dekás''), meaning "ten", and πούς (''poús''), meaning "foot", is a large order (biology), order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfis ...

. The

eggs An egg is an organic vessel in which an embryo begins to develop. Egg, EGG or eggs may also refer to: Biology * Egg cell, the female reproductive cell (gamete) in oogamous organisms Food * Eggs as food Places * Egg, Austria * Egg, Switzerland ...

of aeglids hatch as juveniles which closely resemble the adults. They are cared for by their parents and live at the bottom of the body of water.

Extant taxa

''Aegla'', the only

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

genus in the family, contains around 74 described extant species. Of the 63 species and subspecies described by 2008, two are found in lakes, four in

caves Caves or caverns are natural voids under the Earth's surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground (such as rock ...

, and the remaining 57 are found mainly in rivers. 42 species are found in

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

, all restricted to the country's southern and southeastern regions (

Rio Grande do Sul Rio Grande do Sul (, ; ; "Great River of the South") is a Federative units of Brazil, state in the South Region, Brazil, southern region of Brazil. It is the Federative units of Brazil#List, fifth-most populous state and the List of Brazilian s ...

alone is home to 24). Other countries with species are

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

and

Uruguay Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the A ...

. More than a third of the species are considered

threatened A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...

, and in Brazil alone 26 species are officially recognized as threatened, including 8

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

Species

This list contains all the described species : *'' Aegla abtao'' Schmitt, 1942 *'' Aegla affinis'' Schmitt, 1942 *'' Aegla alacalufi'' Jara & López, 1981 *'' Aegla araucaniensis'' Jara, 1980 *'' Aegla bahamondei'' Jara, 1982 *'' Aegla brevipalma'' Bond-Buckup & Santos ''in'' Santos ''et al.'', 2012 *'' Aegla camargoi'' Buckup & Rossi, 1977 *'' Aegla castro'' Schmitt, 1942 *''

Aegla cavernicola The Aeglidae are a family of freshwater crustaceans currently restricted to South America. They are the only anomurans to be found in fresh water except for a single hermit crab species, '' Clibanarius fonticola'', on Espiritu Santo, Vanuatu. The ...

'' Türkay, 1972 *'' Aegla cholchol'' Jara & Palacios, 1999 *'' Aegla concepcionensis'' Schmitt, 1942 *'' Aegla denticulata'' Nicolet, 1849 *''

Aegla expansa The Aeglidae are a family (biology), family of freshwater crustaceans currently restricted to South America. They are the only anomurans to be found in fresh water except for a single hermit crab species, ''Clibanarius fonticola'', on Espiritu Sa ...

'' Jara, 1992 *'' Aegla franca'' Schmitt, 1942 *'' Aegla franciscana'' Buckup & Rossi, 1977 *'' Aegla georginae'' Santos & Jara ''in'' Santos ''et al.'', 2013 *''

Aegla grisella The Aeglidae are a family of freshwater crustaceans currently restricted to South America. They are the only anomurans to be found in fresh water except for a single hermit crab species, '' Clibanarius fonticola'', on Espiritu Santo, Vanuatu. The ...

'' Bond-Buckup & Buckup, 1994 *'' Aegla hueicollensis'' Jara & Palacios, 1999 *'' Aegla humahuaca'' Schmitt, 1942 *'' Aegla inconspicua'' Bond-Buckup & Buckup, 1994 *'' Aegla inermis'' Bond-Buckup & Buckup, 1994 *'' Aegla intercalata'' Bond-Buckup & Buckup, 1994 *'' Aegla intermedia'' Girard, 1855 *'' Aegla itacolomiensis'' Bond-Buckup & Buckup, 1994 *'' Aegla jarai'' Bond-Buckup & Buckup, 1994 *'' Aegla jujuyana'' Schmitt, 1942 *'' Aegla laevis'' (Latreille, 1818) *'' Aegla lata'' Bond-Buckup & Buckup, 1994 *'' Aegla leachi'' Bond-Buckup & Buckup ''in'' Santos ''et al.'', 2012 *'' Aegla leptochela'' Bond-Buckup & Buckup, 1994 *'' Aegla leptodactyla'' Buckup & Rossi, 1977 *'' Aegla ligulata'' Bond-Buckup & Buckup, 1994 *'' Aegla longirostri'' Bond-Buckup & Buckup, 1994 *'' Aegla ludwigi'' Santos & Jara ''in'' Santos ''et al.'', 2013 *'' Aegla manni'' Jara, 1980 *'' Aegla marginata'' Bond-Buckup & Buckup, 1994 *'' Aegla manuniflata'' Bond-Buckup & Santos ''in'' Santos ''et al.'', 2009 *'' Aegla microphthalma'' Bond-Buckup & Buckup, 1994 *'' Aegla muelleri'' Bond-Buckup & Buckup ''in'' Bond-Buckup ''et al.'', 2010 *'' Aegla neuquensis'' Schmitt, 1942 *''

Aegla oblata The Aeglidae are a family of freshwater crustaceans currently restricted to South America. They are the only anomurans to be found in fresh water except for a single hermit crab species, '' Clibanarius fonticola'', on Espiritu Santo, Vanuatu. The ...

'' Bond-Buckup & Santos ''in'' Santos ''et al.'', 2012 *''

Aegla obstipa The Aeglidae are a family of freshwater crustaceans currently restricted to South America. They are the only anomurans to be found in fresh water except for a single hermit crab species, '' Clibanarius fonticola'', on Espiritu Santo, Vanuatu. The ...

'' Bond-Buckup & Buckup, 1994 *'' Aegla occidentalis'' Jara, Pérez-Losada & Crandall, 2003 *'' Aegla odebrechtii'' Müller, 1876 *'' Aegla papudo'' Schmitt, 1942 *'' Aegla parana'' Schmitt, 1942 *'' Aegla parva'' Bond-Buckup & Buckup, 1994 *'' Aegla paulensis'' Schmitt, 1942 *'' Aegla perobae'' Hebling & Rodrigues, 1977 *'' Aegla pewenchae'' Jara, 1994 *'' Aegla plana'' Buckup & Rossi, 1977 *'' Aegla platensis'' Schmitt, 1942 *'' Aegla pomerana'' Bond-Buckup & Buckup ''in'' Bond-Buckup ''et al.'', 2010 *'' Aegla prado'' Schmitt, 1942 *'' Aegla renana'' Bond-Buckup & Santos ''in'' Santos ''et al.'', 2010 *'' Aegla ringueleti'' Bond-Buckup & Buckup, 1994 *'' Aegla riolimayana'' Schmitt, 1942 *'' Aegla rossiana'' Bond-Buckup & Buckup, 1994 *'' Aegla rostrata'' Jara, 1977 *'' Aegla saltensis'' Bond-Buckup & Jara ''in'' Bond-Buckup ''et al.'', 2010 *'' Aegla sanlorenzo'' Schmitt, 1942 *'' Aegla scamosa'' Ringuelet, 1948 *'' Aegla schmitti'' Hobbs III, 1979 *'' Aegla septentrionalis'' Bond-Buckup & Buckup, 1994 *'' Aegla serrana'' Buckup & Rossi, 1977 *'' Aegla singularis'' Ringuelet, 1948 *'' Aegla spectabilis'' Jara, 1986 *'' Aegla spinipalma'' Bond-Buckup & Buckup, 1994 *''

Aegla spinosa The Aeglidae are a family of freshwater crustaceans currently restricted to South America. They are the only anomurans to be found in fresh water except for a single hermit crab species, '' Clibanarius fonticola'', on Espiritu Santo, Vanuatu. The ...

'' Bond-Buckup & Buckup, 1994 *'' Aegla strinatii'' Türkay, 1972 *'' Aegla talcahuano'' Schmitt, 1942 *'' Aegla uruguayana'' Schmitt, 1942 *'' Aegla violacea'' Bond-Buckup & Buckup, 1994

Fossil taxa

''Haumuriaegla''

''Haumuriaegla glaessneri'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

known only from fossils of Haumurian age (

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

) found near

Cheviot, New Zealand Cheviot () is a town in the Hurunui District of north Canterbury, on the east coast of the South Island of New Zealand. It is located on State Highway 1, approximately north of Christchurch and south of Kaikōura. History and naming The gove ...

. At the time of its discovery, ''Haumuriaegla'' was the only known fossil from the family and the only marine member.

''Protaegla''

''Protaegla miniscula'' was discovered in rocks of

Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...

age from the

Tlayúa Formation The Tlayúa Formation is an Cretaceous Konservat-Lagerstätte near Tepexi de Rodríguez, Puebla, Central Mexico. It consists of three members (Lower, Middle and Upper), spanning the lower Albian of the Early Cretaceous to the lower Cenomanian of ...

, near

Tepexi de Rodríguez Tepexi de Rodríguez (municipality) is a town and municipality in the Mexican state of Puebla in south-eastern Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin Americ ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

Evolution

The family as a whole is thought to have originated around 75 million years ago in a marine environment, and then entered South America from 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 the definition, to Antarctica in the south, and is bounded by the cont ...

side during the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

References

External links

* {{Authority control Anomura Freshwater crustaceans of South America Extant Albian first appearances Decapod families Taxa named by James Dwight Dana