More Information

Additional Information

Hypsibius dujardini

By Fionna Surette

Geographic Range

Hypsibius dujardini, a type of tardigrade or water bear, is a cosmopolitan species. It has been found in the Palearctic, Neotropical, Nearctic, Afrotropical, Antarctic, and Indomalaysian regions. In the Palearctic region, specifically Svalbard, Norway, more than 83 species of tardigrades have been identified, including H. dujardini. In the Nearctic region, H. dujardini is the most commonly-found species of tardigrade. In North America, it has been collected in the United States (Arkansas, California, District of Columbia, Louisiana, Maryland, North Carolina, New York, and Tennessee), Canada (New Brunswick), and Greenland. (McFatter, et al., 2007; Meyer, 2001)

Habitat

Hypsibius dujardini is a freshwater tardigrade that has been collected from sediment of lakes, rivers, and streams. It also is found in association with algae, bryophytes, and vascular plants in these habitats, as well as in cryoconite holes on glaciers. Population density within bodies of water varies based on depth and season. Freshwater tardigrades, like H. dujardini, have been collected at a depth of 23 m in both Lakes Erie and Michigan of the Great Lakes. (McFatter, et al., 2007)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • Range depth
    0 to 23 m
    0.00 to 75.46 ft
  • Average depth
    0.0 - 0.01 m
    ft

Physical Description

Fully-developed tardigrades exhibit bilateral symmetry, are approximately 0.50 mm in length, and have four sets of legs that are roughly evenly-spaced along the length of the body cavity. A waxy cuticle covers the body surface. Females tend to be larger than males. Hypsibius dujardini can be distinguished by its claws, buccal-pharyngeal apparatus, cuticle, and length. Eight morphologically-different claw sets are used to compare tardigrades. This species possesses two branched claws that face directly opposite each other and differ in length. The buccal-pharyngeal apparatus, more simply known as the feeding apparatus, consists of a muscular buccal ring and buccal tube which work together to allow for adhesion and sucking. Apophyses for the insertion of the stylet muscles (AISMs) are a point of comparison when identifying tardigrade species. Hypsibius dujardini has AISMs that are more hooked in appearance than other species. Additionally, the cuticle of H. dujardini is smoother than that of similar species. The metabolic rate of H. dujardini has not been reported, though Macrobiotus hufelandi, another moss-dwelling tardigrade, was shown to have an oxygen consumption rate of (980 µl x 10-6) per hour when in an active life stage. (Coulson, 2000; Guidetti, et al., 2012; Nelson and Marley, 2000; Pigon and Weglarska, 1955; Pilato, et al., 2013)

  • Sexual Dimorphism
  • female larger
  • Average length
    0.50 mm
    0.02 in

Development

Iteroparous females lay an average of 3 to 4 eggs per reproductive cycle, and these take 4 to 4.5 days to hatch. In a laboratory environment this increases to 13 to 14 days. Molting occurs throughout the life of H. dujardini, usually between 4 to 12 times. Each molt takes 5 to 10 days, as the claws, cuticle, and hindgut are all shed. This includes the buccal-pharyngeal apparatus, so the tardigrade is unable to eat immediately after molting. (Bertolani, 2001; Gabriel, et al., 2007; Glime, 2013a)

Reproduction

There is no information available regarding the mating habits of this tardigrade. However, sexual reproduction is not always necessary, as this species can reproduce via meiotic parthenogenesis. (Bertolani, 2001)

When Hypsibius molts, the resulting shed is used as a place to deposit eggs for development. Sexual reproduction can occur, as there are usually both males and females present in populations. Hypsibius dujardini also reproduces using parthenogenesis, specifically, meiotic parthenogenesis. This form of reproduction results in a haploid egg that returns to diploid by duplicating chromosomes. Hermaphroditism is rarer than parthenogenesis but has been shown possible under laboratory conditions. Males, females, and hermaphrodites are all iteroparous, meaning they have multiple reproductive cycles within their lifespan. In each cycle, an average of 3 to 4 eggs are laid (range of 1 to 10), and all are independent upon hatching. (Bertolani, 2001)

  • Range number of offspring
    1 to 10
  • Average number of offspring
    3-4
  • Average gestation period
    4 days
  • Average time to independence
    0 minutes

Hypsibius dujardini is not known to provide any parental care to offspring. (Nelson and Marley, 2000)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

Hypsibius dujardini is estimated to live 4 to 12 years in the wild on average. The closest related species to H. dujardini are the freshwater species of Hypsibius which live 1 to 2 years. One explanation for the disparity seen for estimated lifespan of species within the same family is that freshwater species are not able to undergo latency within their lifetime. Tardigrades are not kept in captivity outside of laboratory conditions. This makes expected life span in captivity difficult to estimate, as most published papers have intentionally altered the environment to limit tardigrade lifespan. (Altiero and Rebecchi, 2001; Glime, 2013a; Nelson and Marley, 2000)

  • Range lifespan
    Status: captivity
    13.25 (high) months
  • Typical lifespan
    Status: wild
    4 to 12 years

Behavior

Hypsibius dujardini is able to respond to external stressors through cryptobiosis, a stress response technique where an individual halts development and metabolism. This is more specifically called and driven by anhydrobiosis, a form of cryptobiosis that is induced by desiccation. In this state, H. dujardini is dehydrated and ametabolic, until water enters their environment and stimulates desiccation emergence. While species was not identified by the authors, a 120-year-old tardigrade was observed emerging from a desiccated state after a moss was rehydrated. Additional early experiments on tardigrades helped establish what temperature and element stressors they are able to survive in.

On the more extreme ends of the spectrum, tardigrades survived exposure to liquid air for 21 months at -200 C. In addition to temperature fluctuation, two species in the same class as Hypsibius dujardini, Milnesium tardigradum and Richtersius coronifer, were shown to successfully resist UV radiation between 116.5 to 400 nm as well as a vacuum with the pressure of space. (Jonsson, et al., 2008; Rebecchi, et al., 2007; Welnicz, et al., 2011)

Communication and Perception

There is no information available on the communication methods or perception of the environment by this particular species. Related species of tardigrades have been found to have sensory organs on their anterior end, and other species have photoreceptors. (Biserova and Kuznetsova, 2012)

Food Habits

Food availability, preference, and morphology of the buccal-pharyngeal apparatus all contribute to food choice of H. dujardini. While there were no food choice experiments involving H. dujardini, other moss-dwelling tardigrades have been studied, and typically feed on algae. The buccal-pharyngeal apparatus has smaller, individual parts working together to support movement of the apparatus as a whole. The parts converge at the pharyngeal tube, where stylets support muscle of salivary glands into the buccal tube. Other tardigrade species have been known to eat nematodes and rotifers as well, though this has not been observed in H. dujardini. (Altiero and Rebecchi, 2001; Glime, 2013a; Nelson and Marley, 2000; Pilato, et al., 2013; Schill, et al., 2011)

  • Plant Foods
  • bryophytes
  • lichens
  • algae

Predation

No research has been conducted on known predators of this species.

Ecosystem Roles

Ballocephala pedicellata is a parasitic fungus that uses moss-dwelling H. dujardini as a host for reproduction. The opportunity for interaction between this host tardigrade and Ballocephala pedicellata comes about naturally, as these tardigrades live and eat there, allowing cohesion and encystment of Ballocephala into the tardigrade. Afterwards, the fungus produces conidospiores (asexual spores), which allow for continual fragmentation within H. dujardini. Zygotes produced by the fungus are also incorporated into the host cell wall, allowing the fungus to remain dormant in the host. (Glime, 2013b; Glime, 2013a; Pohlad and Bernard, 1978)

Commensal/Parasitic Species
  • fungus, Ballocephala pedicellata

Economic Importance for Humans: Positive

There are no known positive effects of Hypsibius dujardini on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Hypsibius dujardini on humans.

Conservation Status

As a tardigrade, Hypsibius dujardini has not been evaluated by the IUCN, and it has no special conservation status supported by any organization.

Contributors

Fionna Surette (author), Radford University, Karen Powers (editor), Radford University, Angela Miner (editor), Animal Diversity Web Staff.

Glossary

Antarctica

lives on Antarctica, the southernmost continent which sits astride the southern pole.

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

biodegradation

helps break down and decompose dead plants and/or animals

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

freshwater

mainly lives in water that is not salty.

herbivore

An animal that eats mainly plants or parts of plants.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

intertidal or littoral

the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

parthenogenic

development takes place in an unfertilized egg

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

References

Altiero, T., L. Rebecchi. 2001. Rearing tardigrades: results and problems. Zoologischer Anzeiger, 240: 217-221.

Bertolani, F. 2001. Evolution of the reproductive mechanisms in tardigrades - a review. Zoologischer Anseiger, 240: 247-252.

Bertolani, R., R. Guidetti, K. Jonsson, D. Boschini, L. Rebechhi. 2004. Experiences with dormancy in tardigrades. Journal of Limnology, 63: 16-25.

Biserova, N., K. Kuznetsova. 2012. Head sensory organs of Halobiotus stenostomus (Eutardigrada, Hypsibiidae). Biology Bulletin, 39/7: 579-589.

Coulson, S. 2000. A review of the terrestrial and freshwater invertebrate fauna of the High Arctic archipelago of Svalbard. Norwegian Journal of Entomology, 47: 41-63.

Gabriel, W., R. McNuff, S. Patel, T. Gregory, W. Jeck, C. Jones, B. Goldstein. 2007. The tardigrade Hypsibius dujardini, a new model for studying the evolution of development. Developmental Biology, 312: 545-559.

Glime, J. 2013. Chapter 5-2: Tardigrade Reproduction and Food. Pp. 521-5216 in Bryophyte Ecology, Vol. 2. Not listed: Michigan Technological University.

Glime, J. 2013. Chapter 5-6: Tardigrade Ecology. Pp. 1-24 in Bryophyte Ecology, Vol. 2. Not listed: Michigan Technological University. Accessed December 05, 2013 at http://www.bryoecol.mtu.edu/chapters_VOL2/5-6Tardigrade_Ecology.pdf.

Guidetti, R., T. Altiero, T. Marchioro, L. Amade, A. Avdonina, R. Bertolani, L. Rebecchi. 2012. Form and function of the feeding apparatus in Eutardigrada (Tardigrada). Zoomorphology, 131: 127-148.

Jonsson, K., E. Rabbow, R. Schill, M. Harms-Ringdahl, P. Rettberg. 2008. Tardigrades survive exposure to space in low Earth orbit. Current Biology, 18/17: R729-R731.

McFatter, M., H. Meyer, J. Hinton. 2007. Nearctic freshwater tardigrades: a review. Proceedings of the Tenth International Symposium on Tardigradia, 66: 84-89. Accessed December 08, 2013 at http://ncate.mcneese.edu/bitcache/a2cec65785d444996580b794b01c2182228f9403?vid=544&disposition=inline&op=view.

Meyer, H. 2001. Tardigrades of Louisiana and Arkansas, United States of America. Zoologischer Anzeiger, 240: 471-474.

Nelson, D., N. Marley. 2000. The biology and ecology of Iotic Tardigrada. Freshwater Biology, 44: 93-108.

Pigon, A., B. Weglarska. 1955. Rate of metabolism in tardigrades during active life and anabiosis. Nature, 176/4472: 121-122.

Pilato, G., M. Binda, R. Catanzaro. 2013. Remarks on some tardigrades of the African fauna with the description of three new species of Macrobiotus Schultze. Tropical Zoology, 4/2: 167-178.

Pilato, G., M. Binda. 2001. Biogeography and limno-terrestrial tardigrades: are they truly incompatible binomials?. Zoologischer Anzeiger, 240: 511 - 516.

Pohlad, B., E. Bernard. 1978. A new species of entomophthorales parasitizing tardigrades. Mycological Society of America, 70/1: 130-139.

Rebecchi, L., T. Altiero, R. Guidetti. 2007. Anhydrobiosis: the extreme limi of desiccation tolerance. ISJ, 4: 65-81.

Schill, R., K. Jonsson, M. Pfannkuchen, F. Brummer. 2011. Food of tardigrades: a case study to understand food choice, intake and digestion. Journal of Zoological Systematics and Evolutionary Research, 49: 66-70.

Welnicz, W., M. Grohme, L. Kaczmarek, R. Schill, M. Frohme. 2011. Anhydrobiosis in tardigrades - the last decade. Journal of Insect Physiology, 57: 577 - 583.

Search

Navigation Links

Information
Pictures
Classification

Classification