In Sight

Masters of camouflage

At the Marine Biological Laboratory, a nonprofit science center seated at the bottom of a seaside hill in Woods Hole, Mass., biologists are raising thousands of animals called cephalopods. These animals — octopuses, cuttlefish and squid — have much to offer biologists: Cephalopods have unusual genetics, unusual bodies and are unusually intelligent.

Euprymna berryi

Euprymna berryi

This hummingbird bobtail squid has a remarkable trait, a gift from iridescent microbes in its body. The squid camouflages itself as a bright night sky. As the bacteria sparkle in the squid’s body, predators lurking nearby mistake the sparkle for the moon shining on the sea.

Metasepia pfefferi

Metasepia pfefferi

Laboratory scientists are raising another species, known as the flamboyant cuttlefish, which has masterful camouflage of its own. Organs called chromatophores, which contain sacs of skin pigment, dot their skin. Small muscles tug those sacs open or closed to rapidly change the cuttlefish’s color.

Roger Hanlon, who has been studying cephalopod camouflage for decades, summarized 10 years of work, 30 journal papers, observations of 800 animals and “a lot of diving” as this: “They only seem to have three to four basic pattern designs that they produce in their skin to create different kinds of camouflage on any background they encounter.”

In other words, cuttlefish can’t perfectly match a coral reef. But the patterns they make are enough to fool eel and fish eyes — and are a vulnerable cuttlefish’s strongest defense in a hungry ocean.

Euprymna scolopes

Euprymna scolopes

The Hawaiian bobtail squid is another small cephalopod that glows with symbiotic bacteria. Its microbes light up in tune with the animal’s circadian rhythm.

Euprymna scolopes

Euprymna scolopes

In August 2018, the National Science Foundation awarded scientists at the Marine Biological Laboratory $300,000 to develop the Hawaiian bobtail squid into a model organism. The squid’s close ties with bacteria make it an “ideal” animal for studying symbiotic relationships, per the NSF award.

Euprymna berryi

Euprymna berryi

This hummingbird bobtail squid, like many of the cephalopods raised at the Marine Biological Laboratory, is a small critter. Male squid grow to about 1.2 inches long, though females get a little bigger — up to 2 inches (about the height of a golf tee).

Sepia bandensis

Sepia bandensis

Stumpy-spined cuttlefish exhibit what’s known as a passing cloud display, in which they send a band of dark color pulsing across their bodies. Biologists do not have a definitive explanation for this signal, which has been observed while the cuttlefish hunt, swim and tend to their eggs

Bobtail squid

Bobtail squid

A bobtail squid in its egg. The outer layer of this squid egg is too tough for glass needles. Instead scientists craft needles out of quartz, which allows them to inject the gene-editing tool CRISPR into squid embryos. Early attempts to create a gene-edited squid show promise, and fully mutant squid will be created in the next few years, predict researchers at the Marine Biological Laboratory.

Bobtail squid

Bobtail squid

A newborn bobtail squid is photographed in a petri dish through a microscope. Most bobtail squid species live for about six months in the wild, said Bret Grasse, who manages the laboratory’s cephalopods. At the science center, he said, the animals live longer and their offspring survive at higher rates.

Octopus chierchiae

Octopus chierchiae

The lesser Pacific striped octopus is so little it could comfortably sit on a half-dollar. In January, the Marine Biological Laboratory announced it was the first facility to breed multiple generations of these animals. After the scientists coaxed the octopuses into mating — no easy feat with the picky, sometimes cannibalistic animals — the researchers tracked the growth of tiny embryos using microscopes and flashlights.

Sepioloidea lineolata

Sepioloidea lineolata

Grasse was the first person in the world to develop a method to raise flamboyant cuttlefish and pyjama squid, seen here, in captivity.

Sepioloidea lineolata

Sepioloidea lineolata

The tiny protrusions behind the striped pyjama squid’s eyes serve an unknown purpose. Perhaps they help this animal bury into sandy sea floors. At the laboratory, cephalopods have “room service to clean up their tanks, and they’ve got free health care,” Grasse said. “They’ve got it pretty good here.”