Posted by Carrie Arnold in Weird & Wild on March 14, 2013
Versión original en inglés.
Most kindergarteners can tell you that an animal eats with its mouth, not its butt.
One species of sea cucumber, however, didn’t appear to get the memo: Scientists have discovered that the giant California sea cucumber (Parastichopus californicus) actually uses its anus as a second mouth.
Scientists already knew that the marine invertebrate, which lives in the shallow ocean waters off the Pacific coast of North America, breathes with its butt.
Because they don’t have lungs, sea cucumbers rely on respiratory trees, a set of long tubes running down either side of the body with a lot of different branches. P. californicus is shaped like a hollow tube, with a mouth at one end and its anus at the other.
The respiratory trees receive oxygen when water is pumped through their anus using the muscles of their cloaca, an opening at the end of the intestinal tract. (Watch a video of sea cucumbers fighting with their guts—literally.)
The 20-inch-long (50-centimeter-long) animal is no slouch: It can pump 3.5 to 4 cups of water per hour through its anus, transferring the oxygen from the water into its respiratory trees, which then oxygenates its cells.
The sheer amount of water flowing into the anus got two invertebrate biologists thinking—since P. californicus sifts plankton and other small particles from water using its tentacles, could it do something similar using its anus?
Though “an animal is not expected to ingest food through its anus”—as William Jaeckle and Richard Strathmann note at the beginning of their study in the March issue of Invertebrate Biology—it turns out the answer is yes.
Multipurpose Anus
Their first hint that the sea cucumber anus was doing triple duty came from a structure called the rete mirabile, a set of blood vessels that connect the sea cucumber’s respiratory trees with its gut.
Initially, Jaeckle, of Illinois Wesleyan University, and Strathmann, of the University of Washington, thought that the rete mirabile was used to transfer oxygen from the respiratory trees to the gut. But if P. californicus were obtaining food via its anus, it would likely use the rete mirabile to transfer the food to the gut. (Watch a video of a hairy sea cucumber.)
To test their idea, the team fed several sea cucumbers radioactive algae, which also contained iron particles. The iron and radioactivity proved an easy way to trace the food as it traveled through the sea cucumber’s body. For instance, areas of the body with the highest concentrations of radioactivity would provide clues about which orifices the animal was using to eat.
Not surprisingly, the results showed that the sea cucumbers ate the algae through their actual mouths, which then traveled through their gut. (See pictures of colorful sea creatures.)
However, the researchers also found a high level of radioactivity when they looked at the rete mirabile. The only way that those blood vessels could have such a high concentration of radioactivity is if the animal was transferring food from the respiratory trees to the gut via the rete mirabile.
Bottom Feeders
When the scientists looked at tissue samples from the sea cucumber under the microscope, they found even more hints that P. californicus was using its anus as a second mouth: They found small pieces of algae and iron in the respiratory trees near the anus. (Also see “Why Sea Slugs Dispose of Their Own Penises.”)
In addition, the sea cucumber’s respiratory trees had small, finger-like projections known as microvilli that are normally found in the gut and aid with nutrient absorption. This also indicated that P. californicus was absorbing food using its anus and respiratory trees.
The authors conclude that although they looked only for evidence of bipolar feeding—the more formal and perhaps polite term for eating with your butt—in one species of sea cucumber, many other species are likely to use this method of feeding.
Bottom line? Eating with your butt may not be all that unusual.
Muchos niños pequeños
pueden decir que un animal come con la boca, no con su parte ano.
Una especie de
pepino de mar, sin embargo, no parece que haya tomado en cuenta esto: Los científicos
han descubierto que los gigantes pepinos de mar de California (Parastichopus Californicus)
utilizan su ano como una segunda boca.
Foto de un pepino
de mar gigante en el Océano Pacífico. Fotografía de Gerald y Buff Corsi.
Los científicos
ya sabían que los invertebrados marinos, que vive en las aguas poco profundas
de los mares frente a la costa del Pacífico de América del Norte, respiran con
su cola.
Debido a que no
tienen pulmones, los pepinos de mar dependen de árboles respiratorios, un
conjunto de tubos largos en ambos lados del cuerpo, con muchas branquias. El
Parastichopus Californicus tiene la forma de un tubo hueco, con una boca en un
extremo y el ano en el otro.
El los árboles
del aparato respiratorio reciben oxígeno cuando el agua es bombeada a través de
su ano con los músculos de su cloaca, una apertura en el final del tracto
intestinal. (Ver un vídeo de los pepinos de mar luchando con sus entrañas -literalmente.)
El animal de 20
pulgadas de largo (50 centímetros de largo) no se queda atrás: puede bombear de
3,5 a 4 tazas de agua por hora a través de su ano, transferir el oxígeno del
agua en sus árboles respiratorios, que oxigena las células.
El pepino de mar
sostenido por un buzo. Lauderdale, Florida. Fotografía de Lois Booth,
La gran cantidad
de agua que fluye por el ano llevó a los biólogos de invertebrados, a pensar: ya que
el pepino de mar Parastichopus Californicus escarba el plancton y otras partículas pequeñas del
agua usando sus tentáculos, podría hacer algo similar con su ano?
A pesar de ser
"un animal que no se espera que ingiera alimentos a través de su ano"
- como William Jaeckle y Richard Strathmann comentan al comienzo de su estudio
en la edición de marzo de Biología de invertebrados, resulta que la respuesta
es sí.
Un ano multipropósito
Su primera pista que el ano del pepino de mar estaba haciendo triple tarea vino de una
estructura llamada la rete mirabile,
un conjunto de vasos sanguíneos que conectan los árboles respiratorios del
pepino de mar con sus intestinos.
En un principio,
Jaeckle, de la Universidad Wesleyan de Illinois, y Strathmann, de
la Universidad de Washington, consideraron que la rete mirabile se utiliza para
transferir el oxígeno de los árboles del aparato respiratorio hasta los
intestinos. Pero si el Parastichopus Californicus, estaba obteniendo alimentos a
través de su ano, es probable que utilice la rete mirabile para transferir los
alimentos al intestino. (Ver un video de un pepino de mar.)
Pepinos de en
Okinawa, Japón. Fotografía tomada por Gary Hughes.
Para probar su
idea, el equipo alimentó a varios pepinos de mar con algas radiactivas, el cual
también contenía partículas de hierro. El hierro y la radiactividad probó de
manera fácil rastrear la comida, ya que viajó a través del cuerpo del
pepino de mar. Por ejemplo, las zonas del cuerpo con las concentraciones más
altas de radiactividad, proporcionaron pistas acerca de qué orificios el animal estaba usando para comer. Sin sorpresas, los resultados mostraron
que los pepinos de mar comieron las algas a través de sus bocas, luego viajaron
a través de sus intestinos. (Ver imágenes de coloridas criaturas marinas.)
Sin embargo, los
investigadores también encontraron un alto nivel de radiactividad cuando observaron la rete mirabile. La única manera de que los vasos sanguíneos puede tener una
alta concentración de radiactividad era si el animal estuvo transfiriendo la
comida de las vías respiratorias hacia el intestino a través de la rete
mirabile.
Alimentadores del fondo
Cuando los
científicos analizaron muestras de tejido de los pepinos de mar bajo el
microscopio, encontraron aún más indicios de que el Parastichopus Californicus estaba
utilizando su ano como una segunda boca: encontraron pequeños trozos de algas y
hierro en las vías respiratorias cerca del ano. (Ver también " ¿Por qué las Babosas de Mar disponen de su propio Pene")
Además, los árboles
de las vías respiratorias del pepino de mar tenían proyecciones pequeñas, con
forma de dedo, conocido como micro vellosidades, que se encuentran normalmente
en el intestino y ayudan con la absorción de los nutrientes. Esto también
indicaba que el Parastichopus Californicus estaba absorbiendo alimentos
utilizando su ano y los árboles respiratorios.
Los autores
concluyen que, a pesar de que estaban buscando sólo evidencia acerca de la
alimentación bipolar (el término más formal y tal vez más educado para llamar a
la alimentación por el ano) en una especie de pepino de mar, muchas otras
especies son capaces de emplear este método de alimentación.
Después de todo?
Comer por el ano puede no ser tan inusual.
http://newswatch.nationalgeographic.com/2013/03/14/giant-sea-cucumber-eats-with-its-anus/
(traducción Moana-Nui Escuela de Buceo)
---------------------------------------------------------------------
Versión original en inglés.
Most kindergarteners can tell you that an animal eats with its mouth, not its butt.
One species of sea cucumber, however, didn’t appear to get the memo: Scientists have discovered that the giant California sea cucumber (Parastichopus californicus) actually uses its anus as a second mouth.
Scientists already knew that the marine invertebrate, which lives in the shallow ocean waters off the Pacific coast of North America, breathes with its butt.
Because they don’t have lungs, sea cucumbers rely on respiratory trees, a set of long tubes running down either side of the body with a lot of different branches. P. californicus is shaped like a hollow tube, with a mouth at one end and its anus at the other.
The respiratory trees receive oxygen when water is pumped through their anus using the muscles of their cloaca, an opening at the end of the intestinal tract. (Watch a video of sea cucumbers fighting with their guts—literally.)
The 20-inch-long (50-centimeter-long) animal is no slouch: It can pump 3.5 to 4 cups of water per hour through its anus, transferring the oxygen from the water into its respiratory trees, which then oxygenates its cells.
The sheer amount of water flowing into the anus got two invertebrate biologists thinking—since P. californicus sifts plankton and other small particles from water using its tentacles, could it do something similar using its anus?
Though “an animal is not expected to ingest food through its anus”—as William Jaeckle and Richard Strathmann note at the beginning of their study in the March issue of Invertebrate Biology—it turns out the answer is yes.
Multipurpose Anus
Their first hint that the sea cucumber anus was doing triple duty came from a structure called the rete mirabile, a set of blood vessels that connect the sea cucumber’s respiratory trees with its gut.
Initially, Jaeckle, of Illinois Wesleyan University, and Strathmann, of the University of Washington, thought that the rete mirabile was used to transfer oxygen from the respiratory trees to the gut. But if P. californicus were obtaining food via its anus, it would likely use the rete mirabile to transfer the food to the gut. (Watch a video of a hairy sea cucumber.)
To test their idea, the team fed several sea cucumbers radioactive algae, which also contained iron particles. The iron and radioactivity proved an easy way to trace the food as it traveled through the sea cucumber’s body. For instance, areas of the body with the highest concentrations of radioactivity would provide clues about which orifices the animal was using to eat.
Not surprisingly, the results showed that the sea cucumbers ate the algae through their actual mouths, which then traveled through their gut. (See pictures of colorful sea creatures.)
However, the researchers also found a high level of radioactivity when they looked at the rete mirabile. The only way that those blood vessels could have such a high concentration of radioactivity is if the animal was transferring food from the respiratory trees to the gut via the rete mirabile.
Bottom Feeders
When the scientists looked at tissue samples from the sea cucumber under the microscope, they found even more hints that P. californicus was using its anus as a second mouth: They found small pieces of algae and iron in the respiratory trees near the anus. (Also see “Why Sea Slugs Dispose of Their Own Penises.”)
In addition, the sea cucumber’s respiratory trees had small, finger-like projections known as microvilli that are normally found in the gut and aid with nutrient absorption. This also indicated that P. californicus was absorbing food using its anus and respiratory trees.
The authors conclude that although they looked only for evidence of bipolar feeding—the more formal and perhaps polite term for eating with your butt—in one species of sea cucumber, many other species are likely to use this method of feeding.
Bottom line? Eating with your butt may not be all that unusual.
http://newswatch.nationalgeographic.com/2013/03/14/giant-sea-cucumber-eats-with-its-anus/
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