In the vast ocean, without walls and far from the floor,  jellyfish can become drifting islands of activity. Creatures from far and wide will congregate on them to act out the ups and downs of life and death. Jellyfish have symbiotic relationships with living things of all sizes, from fish and shrimp that feed off them or off the pieces of food left between their tentacles, to single-celled photosynthesizing organisms that take shelter inside the cytoplasm of the jellyfish’s cells.

In this video, Trisha Towanda talks about one particular jellyfish, the fried egg jelly, and some of the other creatures that hang around it. There are moon jellies that the fried egg jelly eats. These moon jellies have little parasitic crustaceans on them called amphipods, which jump to the fried egg jelly while the moon jelly is being eaten. There are also crabs that ride around on the fried egg jelly, that are parasitic in their youth, but then grow to be helpful symbionts by eating off the little amphipods. This sort of coming of age story, where a symbiont’s relationship changes over its lifespan is an unusual one. Trisha put the pieces together by staring at them for hours and days and weeks when she was in Erik Thuessen’s lab at Evergreen State College.

Many thanks to Trisha Towanda, who is now stationed in the Seibel lab at the University of Rhode Island. This video was edited and animated by Sophia Tintori, with an original score by local pop hero Amil Byleckie. It is released under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license. Here is the paper Trisha wrote about the story.

Rebecca Helm, a Dunn lab graduate student, left a couple of bowls of salt water and hydroids out on the table overnight, instead of the refrigerator where they usually live at around 50 or 60 degrees fahrenheit. The next day she came in and found them doing this:

This particular animal is called Podocoryna carnea. Like most jellies and close relatives of jellies, it has a pretty elaborate life cycle. This one involves a free swimming jellyfish, and a larva that swims around then lands on the back of a hermit crab’s shell. Then the larva metamorphoses into a polyp, which buds more polyps, growing into a whole colony on the crab’s back. The colony is made up of lots of polyps that are all connected and share fluid through a web of tubes that circulate partially digested food. Some members of this colony will eventually bud new swimming jellyfish.

The video at the top is of one of the colonies we have growing in our lab. These polyps were given to us by friends, but they can also be collected from hermit crabs at the beach, then grafted onto slides. They seem to grow well on slides, and slides are much easier to take care of then crabs.

Some of the polyps in the video have pink balls growing around the top. These are the buds that will mature to become free-swimming jellyfish. If you look closely, you can see jellies of all stages of maturity growing, including some that are ready to break free. After they swim off they will continue growing. We’ll try to follow up on how that goes.

Video by Sophia Tintori, life cycle drawing by Perrin Ireland, both released under a Creative Commons Attribution-Noncommercial-Share Alike license. Thanks to Diane Bridge and Neil Blackstone for the Podocoryna colonies. Check out this earlier post of the other polyps we saw budding jellyfish in our lab.

There are different ways to think of individuality. Individuality can refer to function- whether an organism operates and interacts with the world as a unit. A fish is a functional individual, but so is an ant colony. Individuality can refer to evolutionary descent. In this respect our liver is not an individual, there was no ancestral free-living livers out there that our liver is descended from. But our mitochondria are individuals in this sense. They evolved from free-living bacteria that became incorporated into other cells. Individuality can also refer to the process of evolution. In this sense an individual is any entity that has the properties necessary for evolution by natural selection- it reproduces and has variable heritable properties that influence the chances of survival. This could be a free living cell, a cell in a body, an entire multicellular organism, and even groups of organisms in some cases.

All of these definitions of individuality are in alignment in most of the organisms we are familiar with. A bird, a rose bush, and a fly are all individuals as functional entities, according to their ancestry, and as units of selection. This makes it easy to get lulled into thinking of individuality as a monolithic property.

A siphonophore colony is a functional individual. But a siphonophore colony is made up of many parts that are each equivalent to free living organisms such as sea anemones and “true” jellyfish. So by the evolutionary descent definition it is a collection of individuals. The colony as a whole is acted upon by natural selection, making it an individual in the sense of the process of evolution. But it is entirely unclear whether natural selection can act on the parts within the colony, as it does on our own cells when we get cancer, since we don’t know about the heritability between the parts of the colony.

Siphonophores, by forcing us to disentangle what we mean when we call something an individual, help us understand the evolutionary origins of individuality. These different aspects of individuality don’t necessarily evolve at the same time, and one or more of them can even be lost. Organisms like siphonophores provide glimpses of these different combinations of individuality.

Most of the stills are plates from the first papers describing siphonophores. They were published from the mid 1800’s to the early 1900’s by Henry Bryant Bigelow, Ernst Haeckel, and Karl Vogt.

The song New Homes is by Lucky Dragons, the siphonophore video is from Dr. Steve Haddock at MBARI, the podcast was produced by Sophia Tintori, and the video is published under a Creative Commons Attribution Non-Commercial Share Alike 3.0 license.

Dr. Phil Pugh is a good friend of the lab, and he also happens to have described more new species of siphonophores than anyone who has ever lived. In the video below, he describes what it’s like to come across a siphonophore in the deep sea with a submarine. What looks like one long body in this video is actually a free-swimming colony of clones — many genetically identical bodies that are all attached. But each body in the group isn’t just like its neighbor. They each do a specific job for the colony. Some individuals will swim, some will catch food, and some will reproduce.

More on siphonophore biology can be found in papers here and here. But we’ll talk about all that later — for now, just take a look.

Footage courtesy of the Bioluminescence lab at the Monterey Bay Aquarium Research Institute. Music graciously provided by Raf Spielman of The Golden Hours. Edited by Sophia Tintori. This podcast is published under a Creative Commons Attribution Non-Commercial No Derivatives 3.0 license.

Emperor Hirohito was a man who wore many hats. Most famously, he was Japan’s head of state during World War Two. As emperor, he was the stoic and elegant embodiment of Japan. But he was also a family man, a poet, and a marine biologist.

Hirohito had the Imperial Biological Laboratory built for him when he was 24, which was substantially upgraded three years later when he became the emperor. It contrasted the rest of the Imperial Household in the plainness and usefulness of its furniture. Plain furniture, such as a trash bin made out of a trophy elephant leg.

He would steal away every Saturday afternoon and most Thursdays when he could, to his lab where he would meet with other biologists to identify and describe the species that they had dredged up from the surrounding waters. He had a gentle touch when working in the field. If collecting from a colony of polyps, he would take only a small bit of each colony and would put the rock carefully back in place, so as to let the rest thrive.

After the war he published 32 books of plates, describing some 23 new species of ascidians, 7 new species of crabs, 8 new species of starfish, and 6 new species of pycnogonids. He conducted the first comprehensive survey of the biodiversity of Sagami Bay, but he was particularly well versed in the tiny tentacled polyps that grew on the sea floor, called hydrozoans. All of his work was published under the name ‘Hirohito Emperor of Japan.’

At the top is a photo of Emperor Hirohito with his wife, whose hat is making her look a bit like a hydrozoan herself. Next down is Emperor Hirohito in the Imperial Laboratory, from E. J. H. Corner’s article about Hirohito’s scientific career. Below that is an illustration of a nudibranch (left) from Opisthobranchia of Sagami Bay (1949), and an illustration of a coral (right) from The Hydrocorals and Scleractinian Corals of Sagami Bay (1968), by Hirohito Emperor of Japan. Below is a photo of Emperor Hirohito in Kurume, also in 1949.

Look what we caught happening in our refrigerator.

While doing a fridge clean-out in the Dunn Lab, graduate student Rebecca Helm took a look at a forgotten bowl of Chrysaora colorata polyps from our friends Chad Widmer and Wyatt Patry at the Monterey Bay Aquarium. These creatures were left over from an RNA extraction we had done earlier for the Cnidarian Tree of Life Project, and were hidden in the back of the fridge, despite the labs strict ‘no pets’ rule.

Upon inspection, Rebecca noticed that the polyps were strobilating! This is a spectacular type of asexual reproduction, which is explained in more depth in Perrin Ireland’s post on the scyphozoan life cycle.

In this video, a polyp has pinched off into a stack of plate-like discs, called ephyrae. When they pop off of the end of the polyp, they each become a free swimming individual, and a direct clone of the parent polyp. Each ephyra will mature into adult bell-shaped jellyfish. Even before they break away from the poly, they are strongly pulsating as they flex their newly developed swimming muscles before birth.

Video by R. Helm and S. Siebert.

Our own lifecycles are pretty simple. Making babies requires sex. Sex creates offspring with new unique combinations of genes. Many organisms are also capable of asexual reproduction, which doesn’t involve sex (as the name implies) and involves only one parent. In most types of asexual reproduction, genes aren’t reshuffled and the offspring are genetic clones of their parent.

Unlike ourselves, many species have lifecycles that combine both  sexual and asexual reproduction. Take the moon jelly, for example. Moon jellies, also known as Aurelia aurita, are perhaps the quintessential jellyfish, with a typical umbrella-like medusa that travels on ocean currents. There is more to their lifecyle, though, than this swimming organism. The swimming medusa does use sex to make babies—but the babies don’t grow directly into swimming medusae. Medusae release their eggs and sperm into the water and these combine to form a zygote (the fertilized egg). The zygote then develops into a planula larva. The planula eventually sinks to the ocean floor and develops into a polyp, an organism that looks nothing like a medusa. Polyps are attached to the ocean floor, usually on a rock or other hard surface, and stay in one place their whole life. They have a mouth surounded by tentacles, just like the more familiar polyps of sea anemones and Hydra. These polyps, however, are incapable of having sex—they cannot make eggs and sperm. Instead, they reproduce asexually. They can asexually produce other polyps, but they can also asexually produce miniature medusae called ephyra. These are pinched off from the polyp’s mouth as if they were a stack of plates, with the most mature medusa on top. The ephyra then swim away, grow into mature medusae, and complete the lifecycle.

Cnidaria is a group of animals that includes – among other things – jellyfish, corals and sea anemones. They take their name from the greek word for nettles (knide) because of to the sting and rash that a close encounter with them can cause. They elicit this response with a particular type of stinging cell that only they possess, the cnidocyte, which is arguably the most complex cell possessed by any animal. When triggered, a cnidocyte releases a hollow harpoon that penetrates prey organisms – or a swimmer’s skin- and injects toxins. These harpoons are microscopic, and there are many types of cnidocytes each with a different type of harpoon. Some create a painless sticky sensation, others are so powerful that a sting from just one cell can cause considerable burning.

The siphonophores, a group of colonial cnidarians, have multiple polyps and medusae that are specialized for tasks such as locomotion, feeding or reproduction. The picture on the left shows a feeding polyp (the prominent white structure in the center) of the siphonophore Nanomia bijuga. This feeding polyp is attached to the stem of the colony, which stretches across the top of this photo. Each feeding polyp has a single tentacle, and this tentacle has side branches with dense batteries of cnidocytes. Most of the cnidocytes are densely packed into a fascinating complex structure – the cnidoband. These are the orange spirals in the photos. The cnidoband ends in a filament (lower part of the picture) which contains sticky cnidocytes. The terminal filament makes first contact to the prey and sticks to it, which then tugs the cnidoband as the prey struggles. The cnidoband then stretches out and its cnidocytes fire as a unit, deploying their deadly power. These Nanomia bijuga were collected using the ROV Ventana with the friendly support of MBARI. Photos by Stefan Siebert.

With the advent of submarine warfare, the ability to locate large underwater objects with SONAR became of prime strategic importance. Active SONAR detects objects by listening for echos from pulses of sound. As SONAR became more widely used, though, some very strange things were seen in the open ocean. At times, the SONAR suggested that the ocean floor was much shallower than maps and direct depth measurements indicated. Ships sitting in one place would also find that the depth of the ocean would appear to change through the course of the day, as if the sea floor were heaving beneath them.

Something was creating a false bottom that the SONAR couldn’t see through. Submarines found that they could dive right through this layer, hiding beneath it and rendering the SONAR above useless. Details about these false bottoms in the open ocean were closely guarded military secrets during World War II.

It had been suspected that the false bottom was made of large groups of animals, but nets sent to this region usually came up empty. Then, in 1963, Eric Barham, a scientist at the US Navy Electronics Laboratory, reported his first-hand observations form aboard the research submarine Trieste. His dives were coordinated with ships above that monitored the position of the false bottom with SONAR. When Trieste arrived at the false bottom it did find animals, and lots of them. They were siphonophores, extremely fragile colonial jellyfish that are notoriously difficult to collect. They are so fragile that they usually turn to slime in nets and pass right through the mesh.

How could something so delicate and gelatinous have such a strong signature on the SONAR, powerful enough to hide entire submarines? Many species of siphonophores have a gas filled float that serves to regulate buoyancy, and possibly to sense which way is up. The siphonophore that was found in the false bottom, Nanomia bijuga (see photo above), has a float that is about a milimeter in diamater, which is predicted to resonate at a frequency very close to the sound pulse used by SONAR. This resonance scatters the sound, and when there are lots of siphonophores the scattering is so thorough that the SONAR can’t penetrate through the swimming jellyfish.

Besides revealing the important impacts of a poorly-known colonial jellyfish on military technology, these findings also indicate how difficult it can be to measure the abundance of jellyfish. They weren’t detected in nets sent to the false bottom, but there were enough of them to hide entire warships. This measurement problem is compounded when we try to establish whether jellyfish are rising or falling in abundance through time. Because they are so difficult to observe, their abundance has likely been dramatically underestimated in the historical record. As we see more jellyfish with improved sampling methods, it is hard to know if they are more numerous than they used to be.

The Nanomia bijuga photo above was taken by Claude Carré at Villefranche. The float is at the upper right of the image. More information on siphonophores can be found at siphonophores.org.

Eric Roettinger and Mattias Ormestad have launched kahikai.org to showcase some of their beautiful animal photographs. Both are postdocs in Mark Martindale’s lab at the University of Hawaii, where I also spent a couple years. In addition to presenting their photos, kahikai (which means “one ocean” in Hawaiian) will be serving as a repository for primary developmental biology data, such as in situ hybridization images. Eric also curates a set of photos he has taken of other subjects at livingonabeach.org.