The Haliplidae are a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of water beetles that swim using an alternating motion of the legs. They are therefore clumsy in water (compared e.g. with the

Dytiscidae The Dytiscidae – based on the Greek ''dytikos'' (δυτικός), "able to dive" – are the predaceous diving beetles, a family of water beetles. They occur in virtually any freshwater habitat around the world, but a few species live ...

or Hydrophilidae), and prefer to get around by crawling. The family consists of about 200

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 appropriat ...

in 5

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

, distributed wherever there is

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

; it is the only extant member of

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

Haliploidea. They are also known as crawling water beetles or haliplids.

Description

The imagines of these beetles are generally oval in shape, with a very convex upperside, and are generally long. They are generally yellowish to light brown in color, frequently with light and dark patterns dotted with 10 or more rows of punctures on the

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

. The family's most distinctive characteristic is the large

coxal In vertebrate anatomy, hip (or "coxa"Latin ''coxa'' was used by Celsus in the sense "hip", but by Pliny the Elder in the sense "hip bone" (Diab, p 77) in medical terminology) refers to either an anatomical region or a joint. The hip region i ...

plates of the hindlegs, which are immobile (though not fused in the centerline) and extend back along the underside to cover most of the

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

base and the hindleg trochanters and femora. They are used as air storage supplementing the air carried under the elytra. The

compound eye A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which disti ...

s are markedly protruding from a smallish head, which bears

antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...

e with 11 segments set upon an antennophore with a conspicuously short base ( scapus). The extension of the

prosternum The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum ( dorsal), the prosternum (ventral), and the propleuron (lateral) on e ...

is broad, with a truncated tip, ending adjacent to the metasternal process. The metasternum has a complete transverse ridge. The slender legs have long swimming hairs on tibiae and tarsi, but are not flattened into "

flippers Flipper may refer to: Common meanings *Flipper (anatomy), a forelimb of an aquatic animal, useful for steering and/or propulsion in water *Alternate name for a swimfin, footwear that boosts human swimming efficiency * Flipper (cricket), a type of ...

". The foreleg tibiae lack the apparatus for antenna cleaning present in many other beetles. Unlike in other

Adephaga The Adephaga (from Greek ἀδηφάγος, ''adephagos'', "gluttonous") are a suborder of beetles, and with more than 40,000 recorded species in 10 families, the second-largest of the four beetle suborders. Members of this suborder are collect ...

, the hindwings are not folded under the elytra, but rolled together apically. Haliplidae

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e have a long and slender body with a tough

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton ( endoskeleton) in for example, a human. In usage, some of the ...

. They can be recognized by their specialized

mouthparts Mouthparts may refer to: * The parts of a mouth ** Arthropod mouthparts The mouthparts of arthropods have evolved into a number of forms, each adapted to a different style or mode of feeding. Most mouthparts represent modified, paired append ...

, carried on a small head. The

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

e and

labium Labium is the Latin word for lip. In English, it may refer to: * Labia, a part of the female external genitalia * Labium (botany), a modified petal in certain monocot flowers, which attracts insects for pollination * Labium (arthropod mouthpart), ...

are adapted to manipulating the

alga Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

e the larvae feed on, while the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

s contain a channel through which fluids are sucked out of the food. The larval legs are short and carry a single claw each, but the forelegs have various adaptations for climbing among

water plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that g ...

s. Respiration is via

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

which are either long and filamentous, or (in ''

Peltodytes ''Peltodytes'' is a genus of water beetle which is native to the Nearctic, Europe, the Near East, and North Africa. ''Peltodytes'' can generally be differentiated from the similar ''Haliplus ''Haliplus'' is a genus of crawling water beet ...

'') short microtracheal extensions; they are carried on the

tergite A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...

s of all sternal and all but the tenth (last) abdominal segments. The latter may be absent, but in the larvae of some Haliplidae it is tapering and ends in two prongs (which are not urogomphi though). The last (third)

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ...

has functional spiracles on the mesothorax and the first to seventh abdominal segments.

Ecology

Haliplids live in the aquatic vegetation around the edges of small ponds, lakes, and quiet streams. Adults are

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

, eating insect eggs, small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

hydrozoa Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specialize ...

n polyps, and algae, while the

e eat only

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...

. The species of ''

'' deposit eggs on the surface of aquatic plants, while ''

Haliplus ''Haliplus'' is a genus of crawling water beetles in the family Haliplidae. There are at least 180 described species in ''Haliplus''. They are found worldwide, except for Antarctica, living among algae and aquatic vegetation at edges of ponds, ...

'' chews out a cavity in the plants for their eggs. There are three

s, and

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...

tion takes place on land in a chamber constructed by the larva. Crawling water beetles are not extensively studied because their interaction with humans is minimal.

Hungerford's crawling water beetle Hungerford's crawling water beetle (''Brychius hungerfordi'') is a critically endangered member of the family Haliplidae of water beetles. The US Fish and Wildlife Service Draft Recovery Plan for the species published in August 2004 estimate ...

(''Brychius hungerfordi'') is an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

found only in

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and t ...

and

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

Systematics

The classification of haliplids as a separate group of

is unquestioned, and most

entomologist Entomology () is the scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such as ara ...

s believe they developed from terrestrial beetles separately from other types of water beetles. For many decades, the family was in need of revision, the last general catalog being published by A. Zimmermann in 1920. B. J. van Vondel produced an updated catalogue of the known Haliplidae taxa. Like predaceous diving beetles (

), the crawling water beetles form an early offshoot of the Adephaga. They still have grooved

e and their tentoriolacinial muscle does not attach to the mesal stipial base. Their larvae, like those of predaceous diving beetles, do not possess eggshell-bursters on the head. It is not yet resolved whether Haliplidae and Dytiscidae are closest relatives, or whether they originated independently from the basal Adephaga.

Genera

The family is not very diverse, with only five

accepted.Haliplidae Species List
at Joel Hallan's Biology Catalog. Texas A&M University. Retrieved on 10 May 2012. Of these, ''Peltodytes'' is probably the most ancestral, though it has a number of autapomorphies. The others have more

synapomorph In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ha ...

ies in common; ''Haliplus'' is the more diverse and appears to include some minor lineages formerly considered independent genera.

References

External links

Haliplidae
Tree of Life {{Taxonbar, from=Q259362 Beetle families Taxa named by Charles Nicholas Aubé