Riley Thompson made this animation about the fascinating lifecycle of narco babies.
We usually don’t think of babies that grow inside their mothers as parasites, but sometimes the lines get very blurry. This is especially true in Narcomedusae, a group of poorly known jellyfish found throughout the world’s oceans. Some species of Narcomedusae (affectionately called narcos by the people that study them) can grow inside their own mother, who provides nourishment and a safe environment for her. The narco babies can then leave their mother, find another jellyfish of an entirely different species, attach to its flesh, and thrive on the nourishment and safe environment it provides. The physiological interaction of baby and host is similar in both cases – the host provides, the baby takes. But in one case the host is providing for its own offspring, in the other it is providing for somebody else’s offspring.
Thanks to Rebecca Helm and Fabien Lombard for their help translating the wonderful paper on narco life cycles: Bouillon, J. (1987) Considérations sur le developpement des Narcomeduses et sur leur position phylogénétique. Indo-Malayan Zoology 4 : 189-278.
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.
These little pinkish crustaceans have set up house inside the muscular pulsating swimming parts of the colonial jellyfish, Nanomia. Out in the deep sea, there are few solid structures to call home, so living things will often take shelter in or on other animals.
Fish or bugs often hang around the tentacles of jellyfish because the jellies catch food there and are likely to drop pieces that can be salvaged. But these crustaceans are taking a different approach. They are living inside of swimming bells that are nowhere near where food is caught and eaten. These powerful little pods contract to push the colony through the water. The amphipods are likely to be taking refuge in the sturdy tissue, and feeding off the jellies flesh from the inside of the swimming bell.
Stefan Siebert, a post-doc in the Dunn lab, took this photograph of a Nanomia that he caught on a collecting trip in California. The gas-filled gland that keeps the colony afloat is hanging off the left side of the page. Three swimming bells for jet propulsion (with one amphipod crustacean in each) are seen in the middle. The part of the colony that feeds, reproduces, protects, and more, starts in the bottom right corner of the photograph. These amphipod crustaceans happen to be very similar to the ones we just made an animation about, that live on the fried egg jelly.
Here is a video from Casey Dunn of some other colonial jellyfish, to get a sense of how this close up photograph fits into the context of the whole colony, and to see how the swimming bells pulsate.
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.
We found more jellyfish being born in our lab this week!
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.
Last month we posted a video of a siphonophore (one of the Dunn lab’s favorite animals) swimming freely in the ocean. In this next installment of CreatureCast, Casey Dunn describes how siphonophores help us question what we think of as an individual.
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.