Terrestrial animal

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Terrestrial animals are

• Saxicolous creatures are rock dwelling. "Saxicolous" is derived from the Latin word saxum, meaning a rock.
• Arenicolous creatures live in the sand.
• Troglofauna predominantly live in caves.

Taxonomy

Terrestrial invasion is one of the most important events in the history of life.^[1][2][3] Terrestrial lineages evolved in several animal phyla, among which arthropods, vertebrates and mollusks are representatives of more successful groups of terrestrial animals.

Terrestrial animals do not form a unified clade; rather, they share only the fact that they live on land. The transition from an aquatic to terrestrial life by various groups of animals has occurred independently and successfully many times.^[3] Most terrestrial lineages originated under a mild or tropical climate during the Paleozoic and Mesozoic, whereas few animals became fully terrestrial during the Cenozoic.

If internal

• Gastrotrichs (hairy-backs) live in transient terrestrial water and go dormant during desiccation
• Rotifers (wheel animals) live in transient terrestrial water and go dormant during desiccation
• Nematodes
  (roundworms) by going dormant during desiccation
• Eutardigrades
  (water bears) live in transient terrestrial water and go dormant during desiccation
• land planarians
  ) require moist habitats and have restricted range
• Nemerteans (ribbon worms in Monostilifera) require moist habitats and have restricted range
• Onychophora (velvet worms) require moist habitats and have restricted range, the only solely terrestrial phylum
• clitellates) require moist habitats, highly diverse and derived from their marine relatives
• water fleas, copepods, and seed shrimp
  )
• gastropods: land snails and slugs
  )
• tetrapods; semiterrestrial members: amphibious fish
  )

Labeling an animal species "terrestrial" or "aquatic" is often obscure and becomes a matter of judgment. Many animals considered terrestrial have a life-cycle that is partly dependent on being in water.

Fossil evidence has shown that sea creatures, likely arthropods, first began to make forays onto land around 530 million years ago, in the Early Cambrian. There is little reason to believe, however, that animals first began living reliably^{[clarification needed]} on land around that time. A more likely hypothesis is that these early arthropods' motivation for venturing onto dry land was to mate (as modern horseshoe crabs do) or to lay eggs out of the reach of predators.^[5] Three groups of arthropods had independently adapted to land by the end of the Cambrian:

Vertebrate terrestrialization

By approximately 375 million years ago^[3] the bony fish best adapted to life in shallow coastal/swampy waters (such as Tiktaalik roseae). Thanks to relatively strong, muscular limbs (which were likely weight-bearing, thus making them a preferable alternative to traditional fins in extremely shallow water),^[8] and lungs which existed in conjunction with gills, Tiktaalik and animals like it were able to establish a strong foothold on land by the end of the Devonian period. In the Carboniferous, tetrapods (losing their gills) became fully terrestrialized, allowing their expansion into most terrestrial niches, though later on some will return to being aquatic and conquer the air also.

Terrestrial gastropods

Many other animal groups solely have terrestrial animals that live like this: land planarians, land ribbon worms, roundworms (nematodes), and land annelids (clitellates) who are very primitive and breathe through skin.

Velvet worms are prone to desiccation not due to breathing through their skin but due to their spiracles being inefficient at protecting from desiccation, like clitellates they demonstrate extensive terrestrial adaptations and differences from their marine relatives including live birth.

Geoplankton

Many animals live in terrestrial environments by thriving in transient often microscopic bodies of water and moisture, these include

Further reading

• ISBN 978-0-253-34054-2
  .
• Cloudsley-Thompson J. L. (1988). Evolution and adaptation of terrestrial arthropods.
  ISBN 978-3-540-18188-0
  .
• Dejours P. et al. (1987). Comparative physiology: life in water and on land. Liviana Editrice, Italy, 556 pp.,
  ISBN 978-0-387-96515-4
  .
• Gordon M. S. & Olson E. C. (1995). Invasions of the land: the transitions of organisms from aquatic to terrestrial life.
  ISBN 978-0-231-06876-5
  .
• Little C. (1983). The colonisation of land: Origins and adaptations of terrestrial animals.
  ISBN 978-0-521-25218-8
  .
• Little C. (1990). The terrestrial invasion. An ecophysiological approach to the origin of land animals. Cambridge University Press, Cambridge. 304 pp.
  ISBN 978-0-521-33669-7
  .
• Zimmer, Carl (1999). At the Water's Edge : Fish with Fingers, Whales with Legs, and How Life Came Ashore but Then Went Back to Sea. New York: Touchstone.
  ISBN 0684856239
  .

This article incorporates CC-BY-2.0 text from the reference[9] and CC-BY-2.5 text from the reference^[10] and CC-BY-3.0 text from the reference^[11]