Motobdella montezuma
Motobdella montezuma is a species of leech which is only found in Montezuma Well, central Arizona, United States. It is a nocturnal pelagic predator that feeds almost exclusively on the endemic amphipod Hyalella montezuma, which it detects using passive sonar and swallows whole. DescriptionAdults of M. montezuma may reach a length of 71 mm (2.8 in) including the suckers at the front and rear.[3] DistributionMotobdella montezuma is closely related to the genus Erpobdella,[4] which includes species that are widespread across North America from Alaska to Mexico.[5] However, M. montezuma is only known to occur in a single pool, Montezuma Well, in the Montezuma Castle National Monument in Yavapai County, Arizona.[6] EcologyMontezuma Well, due to a high carbon dioxide level in the water, is unable to support a population of fish, leaving an ecological niche of predator-free open water. Although there are a number of species of invertebrates living in the well, the diet of M. montezuma consists almost entirely of the endemic amphipod Hyalella montezuma.[6] BehaviorMotobdella montezuma is nocturnal, resting at the bottom of the well during the day, when predatory waterfowl are present.[7] 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.[7] Prey are detected by passive sonar, and swallowed whole. This pattern of diel vertical migration by a leech is only known to occur in Montezuma Well.[7] Life cycleLike many other leeches, M. montezuma is hermaphroditic. Sexual reproduction results in two individuals fertilizing each other, and the resulting eggs are placed in a nutrient-filled cocoon. The cocoon is placed deep enough to avoid the attention of ducks and other predators, and the eggs hatch into self-sufficient juveniles.[7] References
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