Hiding from danger in the deep sea is a very different game than hiding from danger on land. In the sea, not only does a creature have nothing to hide behind, it can’t even camouflage itself, because it’s environment is just clear water. Perhaps not surprisingly, then, many animals of the sea have evolved ways of being transparent.
Here is a semi-interactive video (with the option of a single, non-interactive video here) from CreatureCast alum Sophia Tintori, featuring tips from a handful of ocean-dwellers that each have drastically different approaches to being invisible.
Male kangaroos kick at each other. Male elephant seals gore each other with their large canine teeth. Male Giant Australian cuttlefish also undergo intense competition for females, but besides physically grabbing and biting each other, they also showcase a brilliant pattern on their skin.
Dr. Roger Hanlon who studies cephalopod camouflage at the Marine Biological Laboratory in Woods Hole, MA describes the mesmerizing “passing cloud” pattern and the purpose behind this agonistic display.
This video was taken by a submarine sent down into the ocean to collect deep sea animals. While you’re watching it, pretend you’re driving it remotely from a dark room that’s swaying back and forth, on a boat 600 meters above the submarine, and you’ve been watching marine snow fly by like stars for the last several hours.
One of the perks of working with jellyfish is going to sea to collect them. The Dunn lab occasionally gets the chance to join our friends from the Haddock lab, at the Monterey Bay Aquarium Research Institute (MBARI), on a week-long excursion out into the Pacific Ocean.
About nine scientists from different labs, about five submarine pilots, and a full boat crew leave from Moss Landing aboard the Western Flyer. Once we reach deep water, we stop driving and drop the submarine into the ocean. The submarine that lives on this boat is called Doc Ricketts. It is about 7 feet tall, has propellors, cameras, lights, collecting buckets, spatulas, and measuring instruments. A crane lifts Doc Ricketts off the floor, the floor opens up to reveal the surface of the sea, and the machine is gently lowered into the water.
This is not the type of submarine that people can travel in. Rather, it has a 2.5 mile umbilical connecting it to the boat, where the pilots are driving it around remotely from the control room, while watching a live, high-definition video feed of what the submarine is seeing.
The control room is a dark little cave on the boat. If you are not driving, controlling the camera, or keeping records of the animals, you can sit in the back and watch the marine snow fly by on the screen as the boat rocks deeply back and forth. When someone spots a shadow that looks like an animal, they shout ‘stop!’ and the pilots drive closer to it. Sometimes it turns out to be a decaying blob of sea-lint, but with any luck it’s an intricate radiolarian, or an elusive vampire squid, or some other beautiful creature. After getting a couple of minutes of close-up footage, which is sometimes the only record of the animal as it exists in the wild, we will either collect it in one of the buckets on the submarine, or keep on flying.
By the end of the night, the pilots have brought the submarine back into the boat, hopefully with all 20 collecting buckets full of interesting animals in their native water. Every one lines up and passes the buckets into one of the labs on the ship, and begins sorting through them and looking for their animals. Amidst the excitement, renowned scientists can be heard saying things like ‘Look at this, have you ever seen anything so magenta in your life?’
Some folks will put their animals in the lab’s walk-in refrigerator (with lids, so they don’t slosh out of their bowls with the rocking of the boat) to look at another day. Some will stay up until the wee hours at their microscopes, processing the samples as quickly as they can while the boat speeds through the night to the next destination. In this photograph, Dr. Claudia Mills is gently taking a Paraphyllina out of one of the sampling buckets (from a depth of 2360 meters), so she can draw it and take notes before sunrise, when the submarine will be lowered into the water again.
All of these photographs were taken by Sophia Tintori during a research cruise last year, except the control room photograph, which was taken by Stefan Siebert on a cruise earlier this month. The video of the humbolt squid is also from this recent cruise and it provided graciously by the Monterey Bay Aquarium Research Institute. All photos are released under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license.
This animal is not the most agile swimmer in the sea. It’s called Nautilus, and it is closely related to cuttlefish and snails. But it swims backwards and often bumps into things.
Thankfully, it has a thick shell, and can retreat into it to avoid predators. And it also dives down deep into the sea during the day when it’s not feeding. The longer it spends inside its shell, though, the harder it is to get oxygen, and levels can get dangerously low if it has to wait for a long time without any new water flowing by. While we might try to hold our breath at those depths, Nautilusholds its heart. Nautilus slows its metabolism down, and it can hold its blood in its enlarged vena cava, spacing out its heart beat to once every one or two minutes.
Sea turtles, also fantastic divers, have a similar mechanism of energy conservation. The deeper they go, and colder the waters get around them, the slower their heart beats, going down to two or three times a minute and slowing their energy use to one tenth of what they would normally use on the shore.
Photographs graciously provided by Adrian Reich of the Wessel lab at Brown University. Thanks to Brad Seibel, our favorite mollusc exercize physiologist, for his help fact-checking. More about Nautilus metabolism can be found here.
The slug pictured above, Elysia chlorotica, is a symbiont thief.
Elysia chlorotica eats the alga Vaucheria litorea but does not digest it. The slug cuts open algal filaments and sucks out the contents, transferring the living chloroplasts to its own tissue. Chloroplasts are organisms that have lived symbiotically within plant cells for many millions of years. They harness energy from the sun, which they give to the plant or alga cell they live within. Most animals digest the chloroplasts entirely when they eat plants, but not Elysia. By keeping the chloroplasts intact and transferring them to its own tissue, Elysia allows them to continue photosynthesizing, producing energy for the slug. The slug can then live for months without eating as long as sunlight is available, and can maintain the same chloroplasts for its entire adult life. This is an extremely unique relationship between an animal and plant symbionts.
Many other animals form associations with photosynthetic organisms. Corals such as the one depicted below have a symbiosis with multiple single-celled organisms called zooxanthellae. This is a multiple-level symbiosis because corals house the entire chloroplast-containing zooxanthellae cells within their tissue. This is different from Elysia chlorotica, who has cut out the middleman — instead of incorporating entire cells, it only retains the chloroplasts.
The upper photograph (of Elysia chowing down) was taken by Nicholas E. Curtis and Ray Martinez. The second photograph is courtesy of Mary S. Tyler, and was the cover of PNAS when this paper was published. The lower picture is the coral Porites as photographed by Casey Dunn. You can watch two amazing videos of the slugs in action, here and here, both of which were included in the PNAS paper.
This is the fourth of four contributions from undergraduates in Casey Dunn’s Bio0041 Invertebrate Zoology class. This episode is inspired by the fascinating behavior of the flamingo tongue snail, Cyphoma gibbosum, which is described in further detail in Casey Dunn’s earlier post.
The marine snail Cyphoma gibbosum browses on the polyps of soft corals (top). It appears to have a brightly spotted shell, but when disturbed the spots begin to move (middle) and then retract within the white shell, along with the rest of the animal (bottom). This is possible because the spots are not part of the shell at all. They are patterns on the thin mantle tissue that extends out of the shell opening and up around the snail’s back. Photos by Casey Dunn.
We are pleased to present Episode 1 of CreatureCast, by Sophia Tintori. In this first video, Alison Sweeney talks about work that has been done in the Morse lab on Squid iridescence. Audio production and animations are by Sophia, who normally studies siphonophores in the Dunn lab. Music by Lucky Dragons (here, and slowed down versions of this and this) and Sophia on the musical saw.