When you live in the darkness of the abyss, finding a partner is hard and keeping a partner is even harder. Deep-sea anglerfish, one of the iconic ambassador species of the deep ocean, have found a novel solution to this problem–dwarf males are sexual parasites that latch onto the body of the much larger female anglerfish and then physically fuse to their partner, becoming permanently attached to the point where they share a circulatory and digestive system.
Parasitic dwarf males are uncommon, but not unheard of, throughout the animal kingdom. Osedax, the deep sea bone eating worm, also maintains a harem of dwarf males in a specialized chamber in their trunk. But few species, and no other vertebrates, go to quite the extremes of the anglerfish. And with good reason.
Vertebrate immune systems have a long shared history. The Major Histocompatibility Complex (MHC) is a suite of genes shared among all gnathostomes–the taxonomic group that contains all jawed vertebrates, from fish to fishermen. It creates the proteins which provide the foundation for the adaptive immune system, the core complex which allows bodies to tell self from no-self, detect pathogens, and reject non-self invaders. Suppressing the MHC seriously inhibits a vertebrate’s ability to fight off infection.
Incidentally, not all deep-sea anglerfish have parasitic dwarf males, and the species most often presented as a type specimen in the popular press, the humpback anglerfish Melanocetus johnsonii, is one of several that do not have permanently attached parasitic dwarf males. M. johnsonii males are free-swimming throughout their life, they’re just small and clingy.
[The following is a transcript from a talk I gave at the 2019 Minerals, Materials, and Society Symposium at the University of Delaware in August, 2019. It has been lightly edited for clarity.]
Good afternoon and thank you all for
coming. I want to change tracks for a bit and scan the horizon to think about
what the future of exploration and monitoring in the high seas might look like
because ocean and conservation technology is in the midst of an evolutionary
shift in who has access to the tools necessary to observe the deep ocean.
This is the Area. Areas Beyond National
Jurisdiction, International Waters, the High Seas, the Outlaw Ocean. It’s the
portion of the ocean that falls outside of national EEZs and is held in trust
by the UN under the Convention on the Law of the Sea as the Common Heritage of
Humankind. It covers 64% of the ocean and nearly half of the total surface of
the Earth. It’s also the region in which most major deep-sea mining ventures
intend to operate.
[The following is a transcript from a talk I gave at a side event during Part II of the 25th Session of the International Seabed Authority in July, 2019. It has been lightly edited for clarity.]
I want to change gears this afternoon and talk about a very different kind of mining. For the last two years, Diva and I have been engaged in a data mining project to discover what we can learn and what we still need to learn about biodiversity at hydrothermal vents from the 40-year history of ocean exploration in the deep sea.
“When the RV Knorr set sail for the Galapagos Rift in 1977, the geologists aboard eagerly anticipated observing a deep-sea hydrothermal vent field for the first time. What they did not expect to find was life—abundant and unlike anything ever seen before. A series of dives aboard the HOV Alvin during that expedition revealed not only deep-sea hydrothermal vents but fields of clams and the towering, bright red tubeworms that would become icons of the deep sea. So unexpected was the discovery of these vibrant ecosystems that the ship carried no biological preservatives. The first specimens from the vent field that would soon be named “Garden of Eden” were fixed in vodka from the scientists’ private reserves.”
In the forty years since that first discovery, hundreds of research expedition ventured into the deep oceans to study and understand the ecology of deep-sea hydrothermal vents. In doing so, they discovered thousands of new species, unraveled the secrets of chemosynthesis, and fundamentally altered our understanding of what it means to be alive on this planet. Now, as deep-sea mining crawls slowly towards production, we must transform those discoveries into conservation and management principles to safeguard the diversity and resilience of life in the deep sea.
Though research at hydrothermal vents looms large in the disciplines of deep-sea science, relative to almost any terrestrial system, they are practically unexplored. Over the last 2 years, Drs. Andrew Thaler and Diva Amon have poured through every available cruise report that made a biological observation at the deep-sea hydrothermal vent to assess how disproportionate research effort shapes or perception of hydrothermal vent ecosystems and impacts how we make management decisions in the wake of a new form of anthropogenic disturbance.
In 2001, on an expedition to hydrothermal vent fields in the Indian Ocean, researchers made a bizarre discovery. Clustered in small aggregations around the base of a black smoker was an unusual snail, seemingly clad in a suit of armor. Rather than a single, hard, calcareous structure, the snail’s operculum was covered in a series of tough plates. On recovery to the surface, those plates, as well as the snail’s heavy shell, began to rust. This was an Iron Snail.
You can buy a 5-lb bag of polymetallic nodules from the Clarion-Clipperton Fracture Zone on Amazon, right now.
Depending on your vantage point and how long you’ve participated
in the deep-sea mining community, this will either come as a huge surprise or be
completely unexceptional. Prior to the formation of the International Seabed
Authority, there were no international rules governing the extraction of
seafloor resources from the high seas. Multiple nations as well as private companies
were engaged in exploration to assess the economic viability of extracting
polymetallic nodules and tons of material was recovery from the seafloor for
research and analysis. Some of that material almost certainly passed into
The Rio Grande Rise is an almost completely unstudied,
geologically intriguing, ecologically mysterious, potential lost continent in
the deep south Atlantic. And it also hosts dense cobalt-rich crusts.
The Rio Grande Rise is a region of deep-ocean seamounts
roughly the area of Iceland in the southwestern Atlantic. It lies west of the
Mid-Atlantic Ridge off the coast of South America and near Brazil’s island
territories. As the largest oceanic feature on the South American plate, it straddles
two microplates. And yet, like much of the southern Atlantic deep sea, it is
relatively under sampled.
Almost nothing is known about the ecology or biodiversity of
the Rio Grande Rise.
Hagfish. You love them. I love them. Of all the fish in all the seas, none are more magnificent than the hagfish. Across the world, children celebrate the hagfish by making slime from Elmer’s glue, their own mucous, or just, like, something. Seriously, how is is that toddler hands are always coated in some strange, unidentifiable slime?
2018 was a big year in hagfish science. Below are just a few of my favorite studies.
A hagfish in the high Antarctic? Hagfish have previously never been observed in the shallow waters around Antarctic, but a photograph from 1988 was determined this year to be a hagfish feeding on a large pile of clam sperm in shallow water. Neat!
Incidentally, the reason the photo languished for so long is that it was originally though to be a Nemertean. Because Antarctic Nemertean worms are huge and horrifying.