The Field Guides

Ep. 71 - The Field Guides Go Crikey!


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The guys return to Everglades National Park, again looking for a predator that Daniel wants to get too close to: the American Crocodile (Crocodylus acutus). Listen in as Daniel shares some research, busts croc-related myths, and Steve probably gets a little too excited about how crocs deal with salt water. Bill doesn’t have much to say, but he’s there, too. Enjoy!

This episode was recorded on January 7, 2025 on the Bear Lake Trail in Everglades National Park. The last bit where the guys find the croc was also recorded in the Park, at the Flamingo Marina.

Episode Notes and Links

As promised during the episode, Steve is looking into how crocs process and excrete excess salt. As soon as he gets to the bottom of it, we’ll share it here.

In the meantime, here’s what Bill found when he asked DeepSeek: Crocodiles, like many other marine and estuarine reptiles, have specialized salt glands to help them excrete excess salt from their bodies. These glands, known as salt glands or lingual glands (located on their tongues), actively transport salt ions (primarily sodium and chloride) from their bloodstream into the gland ducts. The salt is then excreted as a concentrated saline solution, which is expelled from the body.

Crocodiles do not chemically change the salt (sodium chloride) into something else. Instead, they filter and concentrate it, allowing them to maintain proper electrolyte balance in their bodies, especially when living in saltwater environments. This process is crucial for osmoregulation, as it prevents dehydration and helps them survive in both freshwater and saltwater habitats.

In summary, crocodiles excrete salt in its original form (sodium chloride) but in a highly concentrated solution, rather than transforming it into a different substance.

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Works Cited

Admin, CrocAttack. “Database.” CrocAttack, CrocAttack, 17 July 2023, crocattack.org/database/

Balaguera-Reina, S. A., M. Venegas-Anaya, V. Beltrán-López, A. Cristancho, and L. D. Densmore III 2018. Food habits and ontogenetic dietary partitioning of American crocodiles in a tropical Pacific Island in Central America. Ecosphere 9(9):e02393. 10.1002/ecs2.2393

Briggs-Gonzalez VS, Basille M, Cherkiss MS, Mazzotti FJ. American crocodiles (Crocodylus acutus) as restoration bioindicators in the Florida Everglades. PLoS One. 2021 May 19;16(5):e0250510. doi: https://pubmed.ncbi.nlm.nih.gov/34010342/

Grigg, Gordon C., et al. Biology and Evolution of Crocodylians. Comstock Publishing Associates, a Division of Cornell University Press ; CSIRO Publishing, 2015. 

Mazzotti Frank J. , Balaguera-Reina Sergio A. , Brandt Laura A. , Briggs-González Venetia , Cherkiss Mike , Farris Seth , Godahewa Avishka 2022.  Natural and Anthropogenic Factors Influencing Nesting Ecology of the American Crocodile in Florida, United States.  Frontiers in Ecology and Evolution Vol. 10.  https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2022.904576 ISSN=2296-701X

Mazzotti, F.J. The American Crocodile in Florida Bay. Estuaries 22, 552–561 (1999). https://doi.org/10.2307/1353217

Mazzoti, Frank. “American Crocodiles (Crocodylus Acutus) in Florida.” Myfwc.Com, University of Florida IFAS Extension, myfwc.com/media/1847/americancrocodilesinfl.pdf. Accessed Dec. 2024. 

Villegas, Alejandro, & Schmitter-Soto, Juan Jacobo. (2008). Feeding habits of the American crocodile, Crocodylus acutus (Cuvier, 1807) (Reptilia: Crocodylidae) in the southern coast of Quintana Roo, Mexico. Acta zoológica mexicana24(3), 117-124. Recuperado en 30 de enero de 2025, de http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0065-17372008000300008&lng=es&tlng=en.

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