What the Heck Is a Nudibranch? with Marine Biologist Jessica Goodheart

[A camera in the ocean in tropical location dips underwater, showing a nearby snorkeler.] 

JESSICA GOODHEART (Assistant Curator, Division of Invertebrate Zoology): If you’ve been snorkeling or swimming in the ocean… 

[Waves lap against rocks covered in sea grasses.]

GOODHEART: … if you’ve been to tide pools …

[Underwater footage of a coral bed, moving towards a strange blue and white blob-shaped creature.]

GOODHEART: …if you’ve been scuba diving, there were nudibranchs there, I can guarantee it.

[A brown slug glides along a rocky area with moss and vegetation.] 

GOODHEART: Think of the slugs in your garden. That’s what they’re closely related to… 

[A nudibranch sea slug with yellow and white coloration on its head and many finger-like projections on its back glides across corals in the ocean.] 

GOODHEART: …but they don’t look anything like that in so many ways.

[Close-up of a cerulean blue nudibranch with purple-ish projections on its head and back.]

GOODHEART: I think their color patterns are honestly what drew them to me the most.

[A very small white nudibranch swims in green-ish water.]

GOODHEART: There are some nudibranchs that are as long as the thickness of your fingernail.

[A very large, red nudibranch with white accents swims gracefully in the water.]

GOODHEART: And there are some as large as a foot or so in length. 

[Jessica Goodheart speaks to camera]

GOODHEART: Some can supposedly get to be a bit larger, but I’ve never seen any of those. 

[Several shots of nudibranchs of very different shapes and colors.] 

GOODHEART: The diversity of sizes in addition to their shapes and colors are part of what makes it a really interesting group to study.

[ON-SCREEN TEXT: “What the Heck is a Nudibranch? with Marine Biologist Jessica Goodheart”]

[Jessica Goodheart waves and speaks to camera from amongst the cabinets in the Invertebrate Zoology wet collections. Cabinet drawers have been pulled open to show many jars of marine invertebrate specimens preserved in ethanol behind her.] 

GOODHEART: Hello, I’m Dr. Jessica Goodheart. I am the assistant curator for mollusks in the division of invertebrate zoology. And here we are in the invertebrate zoology wet collections. 

Malacology is the study of mollusks. 

[An octopus uses its arms to glide across the ocean floor.]

GOODHEART: You can think of things like cephalopods, which are octopus and squid. 

[Clams work to re-bury themselves in the sand during low tide.]

GOODHEART: Bi-valves like clams, mussels…

[Close-up of a snail crawling towards a flower bud.] 

GOODHEART: …and snails, and slugs like you’d find in your garden.  

[A group of black, white, and orange striped nudibranchs rest on a bright orange piece of coral.]

GOODHEART: Nudibranchs are a kind of sea slug. 

[A circle forms around one of the nudibranchs while the rest of the image fades away. A larger circle labelled “sea slugs” appears around the nudibranch with video footage of a different kind of sea slug, indicating that nudibranchs are on part of the larger group that is sea slugs.] 

GOODHEART: All nudibranchs are sea slugs, but not all sea slugs are nudibranchs.

[Goodheart speaks to camera] 

GOODHEART: I can tell you for sure that I know when I first saw a sea slug in the wild, and that’s because my mom has a picture of it. When I was maybe in third grade or something like that. I grew up in California and we did a class trip to tide pools, and I was holding this giant sea slug, the California Sea Hare, which can be quite heavy.  

[A photographs shows a young Goodheart holding a large black sea slug in both hands and smiling at the camera.]

GOODHEART: I can’t remember the exact first time I found a nudibranch, but I know it was docking.

[Footage aboard a boat approaching a dock at the water’s edge.] 

GOODHEART: Docking is where we just go to like floating docks and look on the sides,

[Standing on the dock, a camera is dipped under the water to reveal aquatic plants and swimming jellyfish.] 

GOODHEART: …and if you look down you can see a lot of things growing, like algae and hydroids.  

And often you will just see nudibranchs in there.

[A nudibranch with a transparent tubular body and many brown-and-white projections on its back clings upside-down to a piece of algae.]

GOODHEART: And I do remember the feeling of sort of flipping over a piece of algae and seeing one on it, and that excitement that came from actually seeing it in the wild. That was pretty incredible actually.

[A series of nudibranchs of differing sizes, shapes, and colors.]

GOODHEART: They’re worldwide, in the Arctic, tropics, Antarctic, anywhere in between. And then you’ll find them in incredibly shallow areas like tide pools, high tide, all the way down to the deep sea.  

We estimate that there’s right now around 3,000 described species of nudibranchs, but there could be upwards of six to ten thousand species of nudibranch, based on sort of what we know about the world and how many we’ve found that haven’t been described yet.  

[Goodheart speaks to camera.] 

GOODHEART: And for context, that’s about how many bird species there are, right? There’s about 10,000 species of birds. 

And I think people would probably agree that birds are quite important in terms of the ecosystems and our understanding about the environment. 

[A colorful sea slug moves along a coral or similar structure with lots of plant and algae life around it.] 

GOODHEART: And sea slugs would be the same as well.  

[A white-, black-, and orange-striped nudibranch rests amongst anemones embedded on a stony coral.] 

GOODHEART: They are primarily carnivores, so they’ll eat things like cnidarians, like hydroids, anemones, jellyfish.

[A long blue nudibranch with yellow spots crawls along an orange-and-white sea sponge.] 

GOODHEART: Others eat sponges or bryozoans. 

[A white nudibranch with orange spots holds a smaller brown nudibranch in its mouth.] 

GOODHEART: There’s at least one nudibranch group that actually eats other nudibranchs.

One of the features of nudibranchs is that they actually have shells as larvae. 

[Close-up shot of larval nudibranchs contained in shells filmed under a microscope in Goodheart’s lab.]

GOODHEART: And then when they metamorphose into juveniles, they lose those shells.

[One juvenile who has emerged from its shall swims away from the rest of the larval nudibranchs.] 

GOODHEART: And so they actually evolved a number of ways to defend themselves. Some steal chemicals from their prey, some have bright colors along with those chemicals to sort of tell predators, like “hey, no, don’t eat me, I’m toxic.”

[Underwater footage of critters on a rocky sea bed, including sea stars and starfish. An on-screen label identifies a small, bright yellow nudibranch tucked amongst the other animals.] 

GOODHEART: Some actually are cryptic, so they sort of hide within the thing that they feed on. 

And others sort of have evolved other mechanisms like stealing stinging structures from their prey.

[Several shots of nudibranchs eating anemones under a microscope in Goodheart’s lab.]

GOODHEART: And this is in particular ones that eat cnidarians, things like anemones, jellyfish, hydroids. 

If you’ve been stung by a jellyfish, that sting comes from specialized defensive structures that it has in its cells. 

Nudibranchs are able to sort of eat those animals and take those defenses from them in order to use them themselves. 

[A very small nudibranch moves along the glass of a tank in Goodheart’s lab. A laptop connected to a microscope shows a nudibranch swimming in a container under the microscope.] 

GOODHEART: In my lab I study how they’re actually able to do this process at a molecular level. 

[Goodheart walks to a cabinet in the collections and opens it.]

GOODHEART: Nudibranchs are in here. 

[Goodheart takes out a small jar from the cabinet and brings it towards the camera.]

GOODHEART: So this is actually the Glaucus atlanticus, this is one of the more interesting ones when it’s preserved. 

[Goodheart takes a series of nudibranch specimens in jars down from the cabinet and shows them to the camera. All of the specimens are a uniform tan color, very dissimilar to the colorful nudibranchs we have seen previously.] 

GOODHEART: We have a couple hundred nudibranch specimens here at the museum. One of the downsides to working on nudibranchs is that unfortunately, they lose their color when we preserve them. So they don’t look quite as exciting in the collection as they do in real life.  

We do ultimately try to use one specimen for as many things as possible.

[In the Museum’s cryogenic collection, a technician shows a barcoded vial of tissue sample, places it into a container, and returns it to a large metal freezer tank which billows frozen steam when closed.]

GOODHEART: If we collect a specimen, we might try and take a tissue sample for genetic analysis later.  

This could include freezing it or putting it in ethanol. 

[Goodheart shows some specimens in jars full of ethanol to the camera.] 

GOODHEART: So even if we’re not able to, at the time, think about what questions we might ask, we would have the specimens for later. Having these collections is incredibly useful for being able to sort of continuously ask questions even when we’re not able to continuously collect animals.  

[Goodheart speaks to camera and smiles.]

GOODHEART: It can be overwhelming even at times seeing or thinking about how many questions there are to ask, how much there is to do, how much we don’t know. But that’s part of what’s exciting about being a biologist. 

[CREDITS]