Reports by FLAAR Mesoamerica
on Flora & Fauna of Parque Nacional Yaxha Nakum Naranjo
Peten, and Livingston, Guatemala, Central America

Bull shark (Carcharhinus leucas), the sea monster of the Maya

The Bull Shark (Carcharhinus leucas) can reach a length between 260 – 350cm and a weight of 316.5 kg and its bite is considered the most powerful of any species of shark. It is cosmopolitan in all tropical and subtropical seas, visiting estuaries, ports, inlets, and penetrating freshwater streams. It is the only shark capable of tracing great distances in rivers -3700 Kilometers- from the sea and also, it can inhabit estuaries and fresh waters, such as rivers and lakes, as in, Lago Nicaragua, Nicaragua, and Lake Izabal, Guatemala. Although they seem not to be able to subsist for life and establish populations in those places. But, why can the bull shark adapt to fresh waters? Sulbarán (2017) mentions that “the kidneys, liver and rectal gland of bull sharks can gradually adjust to the salinity of the water in which they are found. When they move into freshwater, their kidneys remove less salt and more urea from the bloodstream through their urine, which is seen as the reverse of the osmoregulation commonly experienced by these animals.”

What is very interesting too is that many representations and remains of sharks have been found in Mesoamerican art and archaeology from the first millennium BC onwards; and even the Maya word xook (pronounced ‘shok’), has been proposed as the origin of the English term, as you can find in the research of Sarah Newman “Sharks in the jungle: real and imagined sea monsters of the Maya”.

You can continue learning more about this amazing shark with the bibliography we prepared for you.


Most helpful articles on this shark

  • SOSA-Nishizaki Oscar, TORU Taniuchi, HAJIME Ishihara and MAKOTO Shimizu
  • 1998
  • The bull shark, Carcharhinus leucus (Valenciennes, 1841), from The Usumacinta River Tabasco, Mexico, with notes on its serum composition and osmolarity. Ciencias Marinas (1998) 24(2): 183-192.


  • NEWMAN, Sarah E.
  • 2016
  • Sharks in the jungle: real and imagined sea monsters of the Maya. Antiquity 90 354 (2016): 1522–1536.


Most helpful web sites on this the Bull Shark,
Carcharhinus leucas
Description, common names, distribution and general information
This article talks about the capacity to habit in fresh water and saltwater


References Cited and Suggested Reading on the Bull Shark, Carcharhinus leucas


  • 1995
  • Plan de Manejo Regional para el Manatí Antillano, Trichechus manatus





  • BURKE, Jack D.
  • 1979
  • The Fresh-Water Shark in Nicaragua. Natl. Geogr. Soc. Res. Rep., 1970 Proj.: 53-63.




  • DÁVILA-Pérez, Cecilia Vanessa, LÓPEZ-Roulet, Airam Andrea and Manolo José GARCÍA-Vettorazzi
  • 2014
  • Utilidad de la biodiversidad como indicador de sostenibilidad para la evaluación de la calidad ambiental de la Costa Este del Pacífico de Guatemala. Universidad San Carlos de Guatemala. Programa Universitario de Investigación. Recursos Naturales y Medio Ambiente. 169 pages.

    Available Online:

    Page 118 mentions the groups of sharks in the Pacific East Cost in Guatemala.


  • DEL MORAL Flores, Luis Fernando and Gerardo PÉREZ PONCE DE LEÓN
  • 2013
  • Tiburones, rayas y quimeras de México. CONABIO. Biodiversitas, 111:1-6

    Available Online:

    Very helpful. Photographs are large enough to be useable. But shows only a fraction of the sharks; surely there are more that are pictured.




  • GUNTER, Gordon
  • 1938
  • Notes on Invasion of Fresh Water by Fishes of the Gulf of Mexico, with Special Reference to the Mississippi-Atchafalya River System. Copeia, 1938(2): 69-72.

    Available Online:


  • HELLMUTH, Nicholas M.
  • 1987e
  • The Surface of the Underwaterworld Iconography of the Gods of Early Classic Maya art in Peten, Guatemala. revised English original of PhD. Dissertation (submitted and accepted 1986). Vol. 1, 306 pages (text). Vol. 2, 255 pages (about 199 pages of line drawings, more than half done specifically for this PhD dissertation).

    I call this “e” because it is English. I call the other edition “d” for Deutsch. I sincerely appreciate Suzanna Reisinger, my helpful trilingual and multi-cultural Swiss-Austrian (Liechtenstein) girlfriend for translating the zillion pages of my dissertation into German.


  • HELLMUTH, Nicholas M.
  • 1987d
  • Monster und Menschen in der Maya-Kunst. 2000 Jahre Kultur aus dem tropischen Urwald. ADEVA, Akademische Druck u. Verlagsanstalt, Graz, Austria. 403 pages 727 illustrations.

    This is the coffee table book edition of the PhD dissertation a year earlier at Karl-Franzens Universitaet, Graz, Austria.


  • JONES, Tom
  • 1985
  • The Xoc, the Shark, and the Sea Dogs: An Historical Encounter. In Fifth Palenque Round Table, 1983, Vol. VII, ed. Virginia M. Fields, pp.

    His bibliography is impressive. Either he has a gigantic personal research library or his university has a comfortable reading room in it’s libraries.

    At least one other scholar (Newman 2016) has found the use of the word shark in the English language before the British sailors reached Mesoamerica. But linguistic research on the word Xoc in Mayan languages is essential irrespective of whether it is the origin of the English word shark. The Spanish word is tiburon, so not suggested to be from local Mayan languages.

    Free download:


  • JONES, Tom, and Carolyn JONES
  • 1991
  • Jaws II: Return of the Xoc. 6th Palenque Round Table, 1986.

    Tom Jones has written many additional articles on the Xoc glyph in Maya hieroglyphic writing. His 1985 opus has the most material, but if you are an epigrapher you can find lots more if you Google Tom Jones, Xoc hieroglyph. The present bibliography is on the Bull Shark in rivers and lakes, inland from the Caribbean Sea.


  • KRITZLER, Henry and Langley WOOD
  • 1961
  • Provisional Audiogram for the Shark, Carcharhinus leucas. Science, 133: 1480-1482.




  • RAMOS LEÓN Andrea María
  • 2004
  • Acuario y Centro de Investigaciones Marinas en Livingston, Izabal.



  • RUÍZ-Alvarado, C. L. and N. MIJANGOS-López
  • n.d.
  • Estudio sobre la Pesquería del Tiburón en Guatemala. Unidad Especial de Ejecución para la Pesca y la Acuicultura.

    Available Online:




  • THOMERSON, Jamie E., THOMAS, B. T. and Ronald L. HAMPEL
  • 1977
  • The Bull Shark, Carcharhinus leucas, from the Upper Mississippi River Near Alton, Illinois. Copeia, 1977(1): 166-168.


  • THORSON, T. B., COWAN, C. M. and D. E. WATSON
  • 1966
  • Sharks and sawfish in the Lake Izabal-Rio Dulce System. Guatemala. Copeia Vol. 1966, No. 3, pages 620-622.

    Available Online:


  • THORSON, T. B.
  • 1971
  • Movement of Bull Sharks, Carcharhinus leucas, between Caribbean Sea and Lake Nicaragua Demonstrated by Tagging. Copeia, Vol. 1971, No. 2, pp. 336-338

    Available Online:


  • THORSON, T. B.
  • 1976
  • Investigations of the Ichthyofauna of Nicaraguan Lakes. University of Nebraska, Lincoln. 663 pp.


  • THORSON, T. B. and LECEY, Edward J.
  • 1982
  • Age, Growth and longevity of Carcharhinus leucas Estimated from Tagging and Vertebral Rings. Copeia, 1982(1): 110-116.

    Available Online:


Helpful web sites for any and all creatures of the Caribbean

There are several web sites that are helpful even though not of a university or botanical garden or government institute.

However most popular web sites are copy-and-paste (a polite way of saying that their authors do not work out in the field). Many of these web sites are click bait (they make money when you buy stuff in the advertisements that are all along the sides and in wide banners also. So we prefer to focus on web sites that have reliable information.
El tiburón toro, la extraordinaria especie capaz de habitar en aguas dulces y saladas (y está en América), Patricia Sulbarán Lovera, BBC Mundo, 2017.


Web sites specifically on the Bull Shark, Carcharhinus leucas
This article talks about the capacity to habit in fresh water and saltwater
Information and distribution map
Description, common names, distribution and general information
Conservation status
Photos and map distribution



First posted, August 2021.
Bibliography and article prepared by Vivian Hurtado, FLAAR Mesoamerica.

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