SURFACE LIFE FIELD GUIDE
The Mysterious Ecosystem at the Ocean’s Surface: Guide to Ocean Surface Life!
Floating life lives on a shifting world. Humans have been fascinated by these strange creatures for centuries. At their most dense, they create living islands in the middle of the open ocean. But they’re nearly impossible to study because we don’t have the tools to find them. We want to change that. We’ve got the satellites, we’ve got the math, but only with your help can we discover these mysterious ecosystems on the ocean’s surface.
Here’s how to join:
Check out our field guide below, join our mailing list for updates, events, and GO SEA science days, and report what you see:
To Report Marine Life:
Join our project at https://www.inaturalist.org/projects/go-sea. Once you’re a member:
1. Keep an eye on the shore and surface for common floating life (field guide below). If you see something, take pictures and upload your observation to the iNaturalist app, or by visiting iNaturalist.org/projects/
1. Keep an eye on the shore and surface for common floating life (field guide below). If you see something, take pictures and upload your observation to the iNaturalist app, or by visiting iNaturalist.org/projects/
2. And if you don’t see floating life? THAT’S GREAT! In order for our study to work, we need observers all over, even places where floating life might not be! So, find a cool organism and report it on iNaturalist.org, and link it to our project. It’s that simple!
To Report Debris:
Plastic is now part of our marine environment, and we’re studying how plastic impacts the surface ecosystem. If you find plastic, report it on the Debris Tracker app, which you can download at https://www.debristracker.
Porpita
Blue button jellies, known by their scientific name Porpita, float on the ocean’s surface using a round disc, and drift where the current takes them. Unlike Velella they do not have a sail, so they are less commonly found far north and far south, and are most abundant in the tropics. Porpita prey on small swimming crustaceans, and produce small jellyfish which reproduce to develop more floating Porpita. While most Porpita are blue, white buttons and gold buttons are not uncommon.
Photo credit: Denis Riek
Photo credit: Denis Riek
Velella
These blue jellies, known as by-the-wind sailors, drift with the wind using a special living sail. Below the sail a collection of tentacles surround a central mouth, and they love to eat small fish and fish eggs. Each Velella can also bud off many tiny jellyfish from its underside, which reproduce to form new baby floating Velella.
Velella can be seen on coasts around the world. They are less common in the tropics, and more abundant in temperate waters. Rarely, they can be found as far north as Alaska and as far south as southern New Zealand. Very small Velella have been described as ‘sticky blue sand’, and are no bigger than sugar crystals. Large Velella can be longer than a human hand.
(Photo credit: Denis Riek)
Physalia
The Portuguese man-o-war Physalia is among the most infamous of surface-dwellers, with a powerful and dangerous sting. The living sail is muscular and must remain wet at all times, so you can sometimes see them bending and moving their sail to dip into the surrounding water. Their tentacles can stretch for tens of meters, and their favorite foods are fish and fish eggs. While they prefer tropical waters, they can be blown onto cooler shores around the world.
(Photo credit: Denis Riek)
(Photo credit: Denis Riek)
Actinecta
If you are very lucky, you may find a rare brown sea anemone with bubbles at its base. These anemones are called Actinecta and we know very little about them. But we’ve heard reports that they’ve been found floating in the middle of the Pacific! So they are out there, if you can find them!
(Photo credit: Denis Riek)
Dosima fascicularis
The only true floating barnacle, Dosima fascicularis, or the buoy barnacle, lives at the ocean’s surface and hunts fast-moving crustacean prey. Young Dosima attach to floating bits of debris (such as feathers, wood, or even plastic) and make an airy float. This float allows Dosima barnacles to eventually outgrow their larval home and drift independently.
(Photo credit: Denis Riek)
Fish
An exceptional diversity of fish spend their early life at the ocean’s surface! This list includes many well-known species from a variety of habitats. Open-ocean fish species include some anchovy, mahi-mahi, marlins, swordfish, amberjack and Atlantic mackerel. But even species from the seafloor live at the surface when young, including lefteye flounder, blenny, goby, and seahorse/seadragon/pipefish. Deep-sea fish with surface young include viperfish and lanternfish. Many young eels, both reef, seafloor, and deep-sea, nocturnally migrate to the surface layer. But while the ocean’s surface may seem like an odd habitat for baby deep-sea fish, they are far from the most unusual! Diverse fish that migrate into freshwater as adults (either as a habitat or spawning ground) rely on the surface. Yearling and sub-yearling salmon of various species consume surface-dwelling prey in the Northern California Current, American and European eels swim from their freshwater rivers and converge in the middle of the North Atlantic to spawn in the Sargasso Sea. Some fish occupy the ocean’s surface for their whole lives, and are even capable of soaring above the waves, including flying fish and some halfbeaks. Others frequent the ocean’s surface, including basking species like sunfish and basking sharks.
(Photo credit: Songda Cai)
Janthina
The violet snails Janthina construct floating bubble rafts by dipping their body into the air and trapping one bubble at a time, which they then wrap in mucus and stick to their float. Favorite foods of Janthina include Porpita, Velella, Physalia, and sometimes even other Janthina (yikes!). If you find Porpita, Velella, or Physalia, there’s a good chance you’ll find a Janthina nearby!
(Photo credit: Denis Riek)
Glaucus
The beautiful and painful Glaucus, known as blue sea dragon, are sea slugs that have taken to life at the surface. They swallow air to stay afloat, and feed on Velella, Porpita, and Physalia. There are likely MANY species of undescribed Glaucus sea slug, in addition to the handful of described speceis. They’re beautiful, but they steal the stinging cells of their prey, so they may give you a zap!
(Photo credit: Denis Riek)
Floating Algae and Plants
The floating seaweeds Sargassum has numerous gas-filled floats that help it remain at the ocean’s surface. These algae create habitat for a variety of Sargassum-associated species, particularly at the western edge of the North Atlantic Subtropical Gyre, known as the Sargasso Sea. In the Pacific the algal genus Turbinaria reproduces with floating fronts. In addition, over 20 species of algal have been found floating at the surface, and eight species of seagrass (though they don’t normally live there).
(Photo credit: Rebecca R. Helm)
Cephalopods
While no cephalopod species is confined to the surface layer permanently, some frequent the surface habitat quite regularly. Female argonaut octopus (Argonauta spp.) dip their paper-like shell into the air, trapping gas bubbles that they use to maintain buoyancy, and you may find their shells on the beach. Many flying squid species stay near the ocean’s surface, and can launch themselves from the water and soar for impressive distances. Some can reach heights of over 3 meters and others can sail for distances up to 55 meters!
(Photo credit: Songda Cai)
Shrimps
Several species of shrimp are associated with floating Sargassum, and may also be found swimming at the surface on their own. These shrimp species include Latreutes fucorum and Hippolyte coerulescens. Surface-living shrimp exhibit a remarkable array of color patterns, including the common surface blue, and ranging to brown and black. Even better, these shrimp can change colors with special structures called chromophores under their hard shells!
(Photo Credit: Rebecca R. Helm)
Halobate
The only true open-ocean insects are called Hallobates, or the `sea skater.’ Similar to their pond-skater cousins, these insects glide on TOP of the ocean’s surface using specialized feet. They can even make little bubble life jackets to pop to the surface when swamped by a wave. Halobates sp. prey on other floating species, as well as small crustaceans below the ocean’s surface. These insects lay eggs on a variety of objects, including floating feathers, wood, plastic etc. so you may find them in places where more drifting objects are present.
Copepods
These small crustaceans are the ‘rice of the sea’–serving as food for millions of species. Some copepods are adapted to live at the ocean’s surface. Though they’re fast and hard to see, if you find some you’ll know right away thanks to their bright blue color. Some are even capable of jumping out of the water to escape predators!
(Figure from https://onlinelibrary.wiley.com/doi/10.1111/mec.12781)
Isopods
Surface-living isopods, also known as ocean rolly pollies, can sometimes be found floating on their own, and other times found attached to drifting debris. We’ve seen brown ones, white ones, and patched ones, but they may come in many colors!
(Photo credit: Rebecca R. Helm)
Lepas
The Common gooseneck barnacle loves floating through the open ocean. These barnacles attach to many different kinds of floating debris, and have long stalks capped by a shelled body. They use specialized legs (yes, legs!) in their shell to filter food, and have even been known to share food with their barnacle raft-mates!
(Photo credit: Linsey Haram)
Anthopleura
These brave coastal anemones sometimes find themselves far out to sea, and we’d love to know where they’re going and what they’re doing out there!
(Photo credit: Wikimedia Commons)
Aglaophenia pluma
These toothed feather hydroids may not look like much on shore, but they coat floating objects in beautiful feathery structures beneath the waves. These creatures are related to jellyfish, but prefer to remain attached to objects rather than drifting all alone!
(Photo credit: Linsey Haram)
Other organisms
In addition to all the species above, many animals can ride on debris. We’ve seen everything from worms to snails to sea slugs and even corals! Favorite floating objects including driftwood, sea beans, and plastic (but anything will do!). Some even live on other floating animals. Rarely, you may even find a floating rock (pumice) or a tar ball covered in life. We refer to these animals as ‘rafters’ and the objects they ride as their rafts. We’d love to know about any and all rafters you see! And don’t worry if you don’t know what it is, we’re here to help!
(Photo credit: Linsey Haram)
Land plants
Forests are not so separate from the open ocean. Driftwood, sea beans, coconuts, and other plant debris can travel far and wide on the ocean’s surface. Let us know what you see!
(Photo credit: Wikimedia Commons)