''Motobdella montezuma'' is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

leech Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented b ...

which is only found in

Montezuma Well Montezuma Well ( yuf-x-yav, ʼHakthkyayva), a detached unit of Montezuma Castle National Monument, is a natural limestone sinkhole near the town of Lake Montezuma, Arizona, through which some of water emerge each day from an underground sp ...

, central

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

. It is a nocturnal pelagic predator that feeds almost exclusively on the endemic amphipod ''

Hyalella montezuma ''Hyalella montezuma'' is a pelagic amphipod. It lives in Montezuma Well, an oasis in central Arizona. It is the only food of the endemic leech ''Motobdella montezuma ''Motobdella montezuma'' is a species of leech which is only found in Mo ...

'', which it detects using

passive sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or ...

and swallows whole.

Description

Adults of ''M. montezuma'' may reach a length of including the suckers at the front and rear.

Distribution

''M. montezuma'' is closely related to the genus '' Erpobdella'', which includes species that are widespread across North America from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...

Mexico Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guate ...

. However, ''M. montezuma'' is only known to occur in a single pool,

, in the

Montezuma Castle National Monument Montezuma Castle National Monument protects a set of well-preserved dwellings located in Camp Verde, Arizona, which were built and used by the Sinagua people, a pre-Columbian culture closely related to the Hohokam and other indigenous peoples of ...

Yavapai County, Arizona Yavapai County is near the center of the U.S. state of Arizona. As of the 2020 census, its population was 236,209, making it the fourth-most populous county in Arizona. The county seat is Prescott. Yavapai County comprises the Prescott, AZ Me ...

Ecology

Montezuma Well, due to a high carbon dioxide level in the water, is unable to support a population of

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% ...

, leaving an

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (fo ...

of predator-free open water. Although there are a number of species of

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s living in the well, the diet of ''M. montezuma'' consists almost entirely of the

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

amphipod ''

''.

Behavior

''M. montezuma'' is

nocturnal Nocturnality is an ethology, animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatures generally have ...

, resting at the bottom of the well during the day, when

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which i ...

are present. As night falls, the leeches swim towards the surface and hunt amphipods near the surface; this is the only instance of a leech hunting in open water. Prey are detected by

, and swallowed whole. This pattern of

diel vertical migration Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The word ''diel'' comes from the Latin ''dies'' day, and means a 24-ho ...

by a leech is only known to occur in Montezuma Well.

Life cycle

Like many other leeches, ''M. montezuma'' is

hermaphroditic In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have se ...

Sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote th ...

results in two individuals

fertilizing Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proc ...

each other, and the resulting

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

are placed in a nutrient-filled cocoon. The cocoon is placed deep enough to avoid the attention of

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a fo ...

s and other predators, and the eggs hatch into self-sufficient juveniles.

References

{{Taxonbar, from=Q3698463 Leeches Freshwater animals of North America Endemic fauna of Arizona Animals described in 1985