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The Atlantic’s version of the famous leaf sheep slug, or Shawn the Sheep. Costasiella ocellifera is a common find if you know where to look, especially prevalent in roadside patches of its Avrainvillea algae home, usually in less than six feet of water
 

With well over 150 documented species of sea slugs, Florida is one of the richest places in the tropical western Atlantic to photograph these remarkable mollusks. It may not have the sheer abundance of Indonesia or the Philippines, but hidden among Florida’s reefs, wrecks, seagrass beds, and even urban waterways is an astonishing diversity waiting to be discovered. You just have to slow down enough to notice it.

Sea slugs reward patience in a way few marine subjects can. Most are smaller than your fingernail. Some resemble shag carpeting, others floating bouquets, and a few seem almost intentionally designed to confuse taxonomists and photographers alike. Their colors range from subtle camouflage to electric blues, brilliant yellows, and fluorescent oranges that hardly seem real.

The animals we casually call “sea slugs” include several different groups of shell-less gastropods. Nudibranchs are simply the best known. Sacoglossans, often called sap-sucking slugs, feed on algae, and some species steal chloroplasts from their meals, incorporating them into their own tissues, where they continue producing energy through photosynthesis. Other species spend their entire lives on hydroids or bryozoans, blending so perfectly with their prey that they remain invisible until viewed through a macro lens.

That specialization is part of what makes Florida’s sea slug fauna so rewarding. Along the reefs of Palm Beach and the Florida Keys, colorful dorid nudibranchs such as Felimida binza and Felimare juliae are regular encounters on sponges and rubble. Beneath local bridges, feather bryozoans become home to Plocamopherus lucayensis, instantly recognizable by its purple, beard-like appendages and its remarkable ability to produce flashes of light when disturbed. Hydroid colonies support an entirely different community of aeolid nudibranchs, including Coryphellina marcusorum, Cuthona herrerai, Orienthella verta, and Learchis evelinae, each adapted to feed on only a narrow range of prey.
 

Felimida binza is a common nudibranch that can be found nearly year round on patches of shells and rubble in the centers of urban canals and channels
 

Plocamopherus lucayensis is a common local nudibranch that has a head reminiscent of a sock puppet. The purple beard is a nice addition! They are plentiful on the feather bryozoans that grow all over South Florida’s waterways
 

Coryphellina marcusorum nudbranchs are a local favorite known for their bright orange egg masses and purple cerata
 

Cuthona herrerai is a nudibranch that lives its whole life on its own food, a type of hydroid from whom it gets its stinging nematocysts
 

The recently renamed Orienthella verta (formerly Coryphella verta) is a hydroid dweller common under local bridges, imaged here using a shimmer background
 

These are Learchis evelinae, a delicate aeolid nudibranch that feeds on hydroids. I’ve photographed them here against a white background so you can see every detail: the translucent body, the orange-tipped cerata, and the way their forms echo the branching structure of the hydroid on which they’re living and feeding
 

Florida’s sacoglossans are equally charismatic. Costasiella ocellifera, the Atlantic counterpart to the famous “leaf sheep,” is surprisingly common if you know where to search, grazing on patches of Avrainvillea algae in canals, lagoons, and even roadside drainage ditches, often in less than six feet of water. Tiny Ercolania species do much the same on other algae, carrying stolen chloroplasts in the cerata on their backs like living solar panels.

Blue Heron Bridge has become one of North America’s premier destinations for sea slug photography because so many of these habitats converge in one place. Seagrass, algae, rubble, hydroids, and artificial structures support an extraordinary diversity of species within a single shore dive. It is also one of the few places where photographers can routinely encounter undescribed species or recently arrived Indo-Pacific newcomers such as Janolus flavoanulatus—a reminder that Florida’s marine fauna continues to change.

Florida even offers opportunities beyond the reef. During spring blackwater dives in the Gulf Stream, pelagic nudibranchs such as Cephalopyge trematoides drift through the open ocean, sometimes gathering to reproduce around the Strawberry Moon.

Sea slug photography changes the way you dive. Large reefs become collections of microhabitats. Hydroid colonies, algae blades, and bryozoans become destinations rather than background. Every patch of rubble, every clump of algae, and every piling has the potential to reveal another species, making even the most familiar dive sites worth exploring, one careful search at a time.
 

A 3mm-long Ercolania fuscata traverses a blade of stalked grape algae (Caulerpa lamourouxii) in its quest to find more chloroplasts to slurp. These little guys come to visit us for a short time in late summer and fall
 

My first time running into a fully adult size Janolus flavoanulatus did not disappoint! This nudibranch is not native to Florida and is our newest Indonesian neighbor under the Blue Heron Bridge. I go to great technical lengths to produce a clean white background in situ without moving or disturbing the animal or environment
 

Cephalopyge trematoides is a pelagic nudibranch which can be found drifting in the Gulf Stream on blackwater dives. This pair was found mating near June’s Strawberry Moon
 

Favorinus egg eater nudibranchs patrol local patches of hydroids, lying in wait until their favorite food of nudibranch and snail eggs are laid by other species
 

This is an undescribed species of nudibranch from the Cuthona genus. I love the red cerata and I think it gets some of its color from the red hydroid it was eating/living on
 

This Cuthona herrerai nudibranch is lit up under fluorescent lighting bright enough to cast a shadow
 

A Cratena minor nudibranch makes its way across the remains of a dead red heart urchin (Meoma ventricosa). These urchins are ubiquitous in South Florida’s urban waterways and act as biological plows, constantly tilling the loose rubble and sand bottom and preventing an overgrowth of algae
 

This Coryphella verta nudibranch really enjoys Arizona green tea! This reddish hydroid reminds me of the rose buds of traditional Japanese art
 

The gold-line sea goddesses (Felimare ruthae) are a seasonal favorite. You can see the eyes very clearly with this specimen, located right behind the rhinophores. Once you see where the eyes are for these dorid species of nudibranchs, their faces get even funnier!
 

Ercolania viridis is a close relative of the nudibranchs but is in fact a sacoglossian slug. These slugs have a superpower where they can steal chloroplasts from the algae they live on and incorporate them into the cerata on their backs where they continue to photosynthesize and produce food for the slug!
 

To see more of Gabe’s work, please give him a follow on Instagram and visit his website, www.shallowseasgallery.com.