Haemadipsidae are a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of "jawed leeches". The latter might be (but probably are not) a natural, monophyletic group of hirudiniform

Hirudiniformes

The Hirudiniformes are one of the currently-accepted suborders of the proboscisless leeches . Their most well-known member is the European Medical Leech, Hirudo medicinalis, and indeed most of the blood-sucking "worms" as which leeches are generally perceived belong to this group...

 proboscisless leeches

Arhynchobdellida

The proboscisless leeches, Arhynchobdellida, are classified as an order of the Hirudinea. But leech taxonomy and systematics will eventually be revised in due time, not because there are many uncertainties about their phylogeny, but because the major clades of clitellate annelids - and whether the...

. The scientific names mean "blood-drinkers". These leeches have five pairs of eyes, with the last two separated by two eyeless segments. Most have two jaws, but some have three. The family is monotypic

Monotypic

In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

, containing only the subfamily Haemadipsinae, though as the family can apparently be divided into two or three distinct lineages, at least one of the proposed splits

Lumpers and splitters

Lumping and splitting refers to a well-known problem in any discipline which has to place individual examples into rigorously defined categories. The lumper/splitter problem occurs when there is the need to create classifications and assign examples to them, for example schools of literature,...

, while not a distinct family, might be a valid subfamily.

Commonly known as jawed land leeches, these annelid

Annelid

The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...

s are known from subtropical and tropical regions around the Indian

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. Well-known Haemadipsidae are for example the Indian Leech (Haemadipsa sylvestris) and the yamabiru or Japanese Mountain Leech (Haemadipsa zeylanica). Members of the family feed on blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

, except Idiobdella which has adapted to eat small snail

Snail

Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

s.

The other notable group of jawed blood-sucking leeches are the aquatic

Aquatic animal

An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

 Hirudinidae. The Xerobdellidae

Xerobdellidae

Xerobdellidae are a small family of "jawed leeches". The latter might be a natural, monophyletic group of hirudiniform proboscisless leeches. Xerobdellidae have three jaws and five pairs of eyes, the fourth and fifth being separated by one or two eyeless segments...

 are sometimes included in the Haemadipsidae, but their status as a distinct family is supported by sequence

DNA sequence

The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...

 analysis of the nuclear 18S and 28S rDNA

RDNA

rDNA may stand for:*ribosomal DNA*recombinant DNARDNA is also an acronym for*Reformed Druids of North America...

 and mitochondrial COI

COI

COI may refer to:Places* City of Industry, CaliforniaPolitics and society* Center of Information, agency that followed the Office of Strategic Services and preceded the Central Intelligence Agency...

 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

s as well as the anatomy

Anatomy

Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...

 of their sexual organs and nephridia; the latter are located at the belly rather than along the body sides as in the Haemadipsidae proper. All Xerobdellidae have three jaws.

Haemadipsidae probably originate in the Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

, more than 150 million years ago (mya). The diversification of the large Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

n genus Haemadipsa probably did not take place until the Eocene

Eocene

The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

, about 50 mya.

Selected genera

• Amicibdella
• Chtonobdella
• Haemadipsa
• Hygrobdella
• Idiobdella
• Malagabdella
• Nesophilaemon
• Philaemon
• Phytobdella

External links

• Japanese Mounain Leech video on Youtube
  YouTube
  YouTube is a video-sharing website, created by three former PayPal employees in February 2005, on which users can upload, view and share videos....