Respiration: Northern two-lined salamanders are a species of lungless salamander that breaths through entirely through cutaneous respiration, breathing through the skin. These salamanders are not fully lungless however as some lungless salamanders still grow lungs while developing inside the egg. These lungs are not functional and shrinks through apoptosis, becoming vestigial, a remnant from a prehistoric ancestor. Lungless salamanders evolved from an ancestor with lungs but lost them millions of years ago during the late Mesozoic period. There are some hypothesis as to why, one of which is to stop them from being buoyant when hunting for benthic invertebrates in streams.
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Foraging: Northern two-lined salamanders forage primarily in benthic environments in streams and rivers for aquatic invertebrates. These include the larva of beetles, midges, horseflies and whatever else they can catch. On rainy nights however, they have been observed leaving the water to forage on land, presumably for small invertebrates. They have even been observed climbing foliage, with over half of individuals found in plants during one study. Perhaps they were accessing a food source that other organisms have yet to make use of.
Sources:
LeGros, David L. "Plant Climbing in the Northern Two-Lined Salamander Eurycea bislineata, in Algonquin Provincial Park, Ontario." The Canadian Field Naturalist, 15 July 2013, www.canadianfieldnaturalist.ca/cfn/index.php/cfn/article/view/1411. Accessed 2 Nov. 2021. Lewis, Zachary R. "Causes and Consequences of Lung Loss in Salamanders." Harvard Library, Harvard University, 2016, dash.harvard.edu/handle/1/26718748. Accessed 3 Dec. 2021. "Northern Two-Lined Salamander." Ontario Nature, 2021, ontarionature.org/programs/community-science/reptile-amphibian-atlas/northern-two-lined-salamander/. Accessed 2 Nov. 2021. Ruben, John A., and Arther J. Boucot. "The Origin of the Lungless Salamander (Amphibia: Plethodontidae)." The University of Chicago Press Journals, The American Naturalist, 1989, www.journals.uchicago.edu/doi/abs/10.1086/284973?journalCode=an. Accessed 3 Dec. 2021. |