En busca de un pulpo en estado salvaje

Matthew Birk busca pulpos en el bosque de kelp cerca de la Isla Santa Catalina. Foto de Mohammad Sedarat.

Until last year, I had never seen an octopus while diving. That might not surprise most divers — after all, octopuses hole up in small dens, are quite excellent at camouflage and are most active at night. As divers go, however, I am more interested in spotting an octopus than most. I am a teuthologist: a biologist who studies octopuses, squids and their relatives (collectively known as cephalopods). Never seeing an octopus on a dive seemed like quite a blemish on my career, so I sought to remedy this problem and do some fantastic diving in the process.

Criamos algunos pulpos desde que eran huevos en el Laboratorio de Biología Marina (Marine Biological Laboratory) en Woods Hole, Massachusetts, para estudiar cómo sus cuerpos se aclimatan a los cambios ambientales. Una de las muchas cosas fascinantes acerca de los pulpos es que aparentemente el capítulo de los libros de texto de la escuela secundaria que describe cómo funcionan los genes no se aplica completamente a ellos.

Information in an animal’s DNA is supposed to be faithfully copied to the temporary middleman known as RNA before that RNA becomes a template for making a protein. Cephalopods, however, get really creative with their RNA. Most animals will make at most a few hundred edits in their RNA that tweak the composition of the resulting proteins. Cephalopods, however, make tens of thousands of these edits and therefore tweak thousands of their proteins to deviate from what is encoded in their genomes. How do they do this and why?

Una vista del puerto deportivo Two Harbors y la zona vecina de búsqueda de pulpos.

En nuestro laboratorio descubrimos que la temperatura del agua influye en muchas de estas ediciones, pero criar pulpos con una calidad del agua cuidadosamente controlada y un horario de alimentación rutinario no representa el mundo real. Quería confirmar que estos efectos que veíamos en el laboratorio estaban, en efecto, presentes en las poblaciones silvestres.

Al nunca haber visto un pulpo durante un buceo, sabía que necesitaba un poco de ayuda para encontrar uno y así poder determinar si exhibían características similares. La persona perfecta era Jenny Hofmeister, Ph.D., una científica ambiental del Departamento de Peces y Vida Silvestre de California (California Department of Fish and Wildlife), que hizo su trabajo doctoral sobre pulpos en la Isla Santa Catalina cerca del sur de California. Ella no solo sabría dónde encontrarlos, sino que también podría ayudarme a obtener un permiso de recolección científica para esta investigación, financiada por la Fundación Nacional de Ciencias (National Science Foundation).

While we traveled to the dive site, I outlined my objectives, research and schedule, while Jenny and her protégé, Mohammad Sedarat, shared their octo-hunting secrets. You’re often not looking for the octopus itself but rather for tantalizing crannies that would make a great den. Octopuses search for somewhere that’s big enough to fit in comfortably but not so roomy that a predatory kelp rockfish can follow them in. A good, clear view unobstructed by algae is a must, and a back exit is a nice feature. Don’t expect to stumble upon an octopus roaming the reef. Think of yourself as a door-to-door salesperson checking every potential home you can find.

Un pulpo de dos puntos de California (Octopus bimaculoides) observa desde su guarida en Catalina.

Sabía que una vez que encontrara un pulpo sería un desafío hacerlo salir de su cómoda guarida y lograr que cayera en mi acogedora bolsa de malla. También tenía que encontrar la misma especie que habíamos criado en el laboratorio: el pulpo de dos puntos de California (Octopus bimaculoides)Fortunately, Jenny and Mohammad are among the best in the business at identification. The trick is distinguishing it from an extremely closely related species, Verill’s two-spot octopus (Octopus bimaculatus). Their appearances, habitats and ecologies are as similar as their scientific names unless you find a female guarding her eggs. Online resources will tell you to look at the iridescent blue ring they display when stressed and consider if you found them in sandy or rocky environments, but these ID markers are not very reliable. I relied instead on my guides’ seasoned eyes and looked for the sign language “A” for Octopus bimaculatus or “O” for bimaculoides.

Un pulpo capturado reposa seguro en el interior de una cubeta para ser transportado al laboratorio marino.

We found a den and identified the first animal. Injecting a small bit of white vinegar into the den behind the octopus might drive him out of the den, so I found a place to empty my 50 mL syringe, hoping not to push him further inside. I waited, trying to look as unsuspecting as possible. Either he’ll pump the vinegar out of his den with his jetting funnel, or he’ll try to make a break for it. But first he’ll make sure the coast is clear. I watched him creep progressively further out of the den, and then I made a quick grab to get him in the bag. I had many failures but enough successes to eventually head back to the boat with some animals to study.

Con los pulpos guardados de manera segura en una cubeta sellada, nos dirigimos de regreso a nuestra base de operaciones en el Centro de Ciencias Marinas Wrigley de la Universidad del Sur de California (University of Southern California Wrigley Marine Science Center) para estudiar a los animales.

A medida que pasaron los días de búsqueda de pulpos entre los abundantes paisajes submarinos de las Islas del Canal, la belleza y la enorme alegría de bucear en esta parte especial del mundo me dejó anonadado. Mi viaje fue científicamente productivo, y finalmente pude ver una infinidad de pulpos mientras buceaba, pero tuve que visitar Catalina durante la época más fría del año para confirmar que la edición sensible a la temperatura estaba ocurriendo en las poblaciones silvestres.

The following February I returned to the island to collect more animals when the water had chilled by about 12°F from the previous summer. After that second trip, with my data-gathering concluded, I found myself wandering around the Los Angeles airport in early March 2020. I could hear a brief news story in the background about a new virus outbreak, and I wondered in passing whether I should wash my hands a bit more just in case.

Octopus “condominiums” housed the animals during controlled-temperature experiments at the Marine Biological Laboratory in Woods Hole, Massachusetts.

Trabajar a la vanguardia de la ciencia puede ser muy emocionante, pero también puede ser sumamente frustrante. Pero resulta que incluso los mejores expertos del mundo a veces pueden estar equivocados. Después de toda mi codificación de barras de ADN descubrí que todos los pulpos que habíamos capturado eran Octopus bimaculatus y no la especie bimaculoides species I was targeting. No one is to blame — we all knew how difficult it is to correctly identify them.

In many ways, that is the beauty of science. New data can show that we aren’t quite as good at understanding nature as we think. New findings can cause us to reassess what we think we know about the beautiful and immensely enigmatic underwater world that divers are privileged to explore. Now instead of merely validating lab-based studies, I am exploring how RNA editing evolves by examining both closely related species.

This is the essence of how science really works: Scientific endeavors are often the curviest path to an answer you weren’t expecting to a question you did not initially set out to ask. But from this messy track comes the discovery of the unknown and progress toward a better understanding of our world.

© Alert Diver — Q3/Q4 2021

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