marine biology

Octopus’s skin detects light the same way its eyes do

Octopuses have a well-known ability to change the color and texture of their skin in order to blend in with their environment or to communicate with other organisms. They are able to do this because of special pigmented organs in their skin, called chromatophores, which receive signals from the animal’s eyes and then expand and contract as needed to change the skin’s appearance. A new study shows that the octopus’s eyes are not the only way that the chromatophores receive these signals, however: octopus skin can change its appearance with no input from the eyes at all.

Researchers at UC Santa Barbara studied the California two-spot octopus (Octopus bimaculoides) and found that its skin changed color when exposed to white light as a result of the chromatophores in the skin contracting, even with no sensory input from the eyes. Further experiments showed that the chromatophores responded the quickest to blue light. This process, called light-activated chromatophore expansion, shows that the chromatophores and light sensors are linked within the skin and do not rely on input from the central nervous system. The skin could not sense light with the same detail as the eyes and brain, with its responses being limited to changes in brightness, but the changes were undeniably there.

Researchers dug deeper and found that sensory neurons in the octopus’s skin contained rhodopsin, a light-sensitive opsin protein found in the octopus’s eyes. This reveals a heretofore-unknown evolutionary adaptation in which cellular mechanisms for light detection in octopuses’ eyes have been adopted by their skin as well.

Other marine molluscs have light-sensing skin, but researchers are not sure if that is the result of opsins or other adaptations. If other molluscs’ skin also uses these proteins to change appearance, researchers hope to discover whether the similar adaptations evolved independently or from a common ancestor.

  • Based on materials originally provided by UC Santa Barbara
  • Journal reference: M. D. Ramirez, T. H. Oakley. Eye-independent, light-activated chromatophore expansion (LACE) and expression of phototransduction genes in the skin of Octopus bimaculoides. Journal of Experimental Biology, 2015; 218 (10): 1513 DOI:10.1242/jeb.110908
  • Image: A California two-spot octopus (Credit: Partial Pressure Production, via marinebio.org)
  • Submitted by volk-morya
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TARA OCEANS: EL VELERO QUE SURCÓ LOS OCÉANOS EN BÚSQUEDA DEL PLANCTON.

Tara es un velero de 36 metros, y con capacidad para albergar 15 personas, pero no fue imprevisto para un equipo de 126 científicos internacionales que lo convirtió en un laboratorio flotante y se hizo a la mar por los cincos océanos, durante más de tres años recogiendo muestras de agua.

La expedición llamada Tara Oceans, ahondó en la biodiversidad y la genética del plancton marino, ocupa hoy cinco artículos, y un número especial en la connotada revista Science.

Desde virus hasta larvas de peces, los investigadores se detuvieron en 210 puntos de las principales zonas oceánicas y recogieron microorganismos de 35.000 muestras de agua de los estratos superficiales donde aún llega la luz solar.

Compuesto por virus, bacterias, arqueas, protistas y pequeños eucariotas multicelulares el plancton produce la mitad del oxígeno de la atmósfera, actúa como sumidero de CO2 minimizando el efecto invernadero y es la base de la cadena trófica marina de la que se alimentan peces, invertebrados y mamíferos.

Fotos

  1. Plancton colectado en el Océano Pacifico -  Christian Sardet/CNRS/Tara Expéditions
  2. Un amfipodo hyperideo - crustaceo parasito que come plancton llamado salpas y usa la cavidad vacías gelatinosa como una concha protectora -  M.Ormestad/Kahikai/Tara Oceans
  3. Tara en el Océano Artico -  A.Deniaud/Tara Expéditions
  4. La ruta del viaje fue elegida para cubrir los principales sistemas oceánicos. / Bepoles / Tara Expéditions
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A small Japanese puffer fish is the creator of one of the most spectacular animal-made structures. To impress the female puffer fish, the male labors 24 hours a day for a week to create a pattern in the sand. If the female finds his work satisfactory, she allows him to fertilize her eggs. She then lays them in the middle of the circle, leaving the male to guard the eggs alone.

Life Story (2014)

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Mimic Octopus

This sea creature can mimic the behaviors and various shapes of different animals it sees. They are highly intelligent and use their ability to camouflage and avoid predators. It is so intelligent that it will actually mimic a sea creature that its predators is afraid of. For example, scientists observed that when the octopus was attacked by territorial damselfishes, it mimicked the banded sea snake, a known predator of damselfishes.

It can mimic sea creatures like the sole fish, lion fish, sea snakes, frog fish and more.

SOURCE

The environmental impact of oysters, in one photo

The water in both tanks came from the same source. The one on the right has bivalves. Not only do oysters naturally filter the waters in which they live, they can even protect humans from destructive hurricanes. For more, read about New York’s efforts to bring back oyster populations in the once-toxic Hudson River.

Delicious AND helpful. Who knew?

(photo via Steve Vilnit on Twitter)

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photos by matt smith from the Illawarra coast in new south wales of bluebottles, violet snails and blue dragons. 

despite its resemblance to the jellyfish, the bluebottle is more closely related to coral. known as a zooid, the bluebottle (or portugese man of war) is a colonial animal composed of many highly specialized and physiologically integrated individual organisms incapable of independent survival. 

the blue dragon – a type of nudibranch, here no larger than a thumbnail, with its own potent sting – is able to eat the nematocysts (stinging cells) of the bluebottle without discharging them and internally relocate them to the tips of each one of the fingers you can see in the pictures.

for their part, the violet snails also feed on the bluebottles.

notes matt, “despite their potentially dangerous sting, the bluebottle is an amazingly beautiful creature. with strong winds, hundreds of these cnidaria are blown into the bays around my home town and trapped overnight.”

this allows him to capture the above shots, which he creates with use of a fluorescent tube in his strobe light and a homemade waterproof lens dome.

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Reaching sizes of at least 16 inches (40 cm), the Spanish Dancer is the largest nudibranch and one of the largest sea slugs on the planet.

Like most nudibranchs, the Spanish Dancer is brightly colored and does not blend in well with its surroundings. This bright coloration, similar to that of the poison dart frogs and many other species, serves as a warning to potential predators that the Spanish Dancer does not taste good and may even make a predator sick. Though this species spends most of its time crawling along the reef surface, it will swim when threatened, violently flapping its external gills and other appendages and displaying its brightest warning colors. This behavior reminded some observers of a flamenco dancer, earning the Spanish Dancer its common name.

via //photo 1: Mauritius100 //photo 2: manaphoto

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Southern fur seal pups in Kaikoura (NZ) have figured out a way to avoid taking their first swim in predator-filled waters. By travelling up a nearby stream, they reach a secluded waterfall pool where they can learn vital swimming skills in complete safety. A pup makes this journey only once, spending 3 days in the pool before returning to the sea with its newfound skills.

Life Story (2014)

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‘Shark Lady’ Eugenie Clark, Famed Marine Biologist, Has Died

A pioneer in marine conservation and the study of shark behavior, Clark helped the public understand and appreciate the much maligned species.

Eugenie Clark, an American marine biologist who fell in love with sharks as a child with her nose pressed against an aquarium tank—and whose research on the much maligned species earned her the nickname “Shark Lady"—died Wednesday morning in Sarasota, Florida. She was 92.

The death was confirmed by National Geographic photographer David Doubilet, her colleague and friend.

A pioneer in the use of scuba gear to conduct underwater scientific research and a veteran of more than 70 deep dives in submersibles, Clark continued diving into her nineties, even after being diagnosed with non-smoking-related lung cancer.

"She never outgrew this absolute fascination of looking and seeing and observing under water,” said Doubilet, an underwater photographer who swam beside Clark for the majority of the dozen National Geographic magazine stories she wrote. “Even when I was a younger man and she was older, I couldn’t keep up with her. She moved with a kind of liquid speed underwater.”

Before Clark began her research on sharks in the 1950s, the animals were considered both dumb and deadly. “After some study,” she said, “I began to realize that these 'gangsters of the deep’ had gotten a bad rap.”

Although she would conduct research on other fish—she discovered several species and had some named in her honor—much of her work was focused on sharks and dispelling the public’s fears about them, especially after the 1975 movie Jaws. One of her National Geographic stories was titled, “Sharks: Magnificent and Misunderstood.”

Clark discovered the first effective shark repellent in secretions from a flatfish called Moses sole that lives in the Red Sea. She ventured into undersea caverns off Mexico’s Yucatán Peninsula to find “sleeping sharks” suspended in the water, a discovery that upended scientists’ belief that sharks had to keep moving to breathe.

“Her contributions were astounding,” Doubilet said.

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And the award for ‘most dedicated mother in nature’ goes to…

…the deep-sea octopus, Graneledone boreopacifica.

This tough mama currently holds the record for longest egg-brooding period of any animal—about 53 months.

Yes, she spent almost 4-and-a-half years guarding her eggs vigilantly from would-be predators, never leaving her spot. The research team that first discovered her via remote-operated vehicle (ROV) revisited her multiple times, only to observe her physically wasting away and looking weaker with each visit.

Why does she do this? To increase her young’s chances of survival. By guarding her eggs over a long period of time, she provides her young with a longer developmental period. G. boreopacific hatchlings emerge as miniature adults, skipping the larval stage entirely.

World’s toughest job indeed. 

Happy mother’s day!

Video source: MBARI

Reference: Robison, et al. 2014.