genus: (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)

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genus: (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)

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genus: Man O' Wars (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)

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genus: (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)

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species: Buoy Barnacle (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)

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genus: Violet Snails (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)

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genus: (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)

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class: Cephalopods (Cephalopoda)

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)

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genus: Sea Skaters (Halobates)

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.

(Figure created by Xavier Pita)

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subphylum: Crustaceans (Crustacea)

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)

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class: Malacostracans (Malacostraca)

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)

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genus: Goose Barnacles (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)

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genus: (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)

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species: Podded Hydroid (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)

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