About the SA Blog Network

Science Sushi

Science Sushi

Real science. Served raw.
Science Sushi Home

Playing in Tide Pools | Scientist in vivo

The views expressed are those of the author and are not necessarily those of Scientific American.

Email   PrintPrint

Here at Science Sushi, I often talk about the great work being done by other scientists, but I rarely turn the focus around and talk about my life as a scientist. This is a shame because I really love my job. So, starting today I’m going to try and take you out in the fiels and into the lab in a series I’ve titled “Scientist in vivo“. I hope that, through this series, you’ll get to learn what it’s like to be a scientist, what I actually do for a living and what makes my job so rewarding. Enjoy!

As a scientist, one of the most important parts of my job is outreach. I consider this blog and other outreach activities as an integral part of my profession. So every year, I wrangle grad students from the Ecology, Evolution and Conservation Biology (EECB) Specialization at the University of Hawaii to help a local elementary school teach their students about the ecology of tide pools. The partnership between EECB and Mililani-Mauka Elementary school is one of those rare gems in outreach where both sides get a tremendous amount out of the relationship. The school gets trained scientific experts that fascinate and amaze the kids with tales of slimy defenses and odd partnerships between crabs and anemones. In turn, the graduate students get to take a day off, get out of the lab, and act like kids playing in tide pools. Sometimes, I think the overworked grad students are more excited to catch critters than the kids!

What can you find in a tide pool on the coast of Oahu? Well, let’s find out…

Hexabranchus saguineus – Spanish Dancer



Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Family: Hexabranchidae
Genus: Hexabranchus
Species: H. sanguineus

One of my favorite finds was a Spanish Dancer nudibranch – a name that aptly fits the beautiful undulating motion of this colorful animal while it swims which looks like the swirling of a flamenco dancer’s skirt. It’s the largest species of nudibranch in Hawaii, and can get over a foot long!

The term “nudibranch” means “nude/naked gills,” and refers to the frilly, external gills found in these species (they look almost like feathers sticking out of the dancer’s back). The scientific name for this species, Hexabranchus sanguineus, refers specifically to the number of gills (six) and to its blood-like red coloring. Nudibranchs are often brilliantly colored and found in many sizes and shapes, which may serve to warn predators as many species are toxic. Unlike other sea critters, toxic nudibranchs don’t make their own defenses – they steal them from species they eat, like sponges and Portuguese man-of-war.

Dardanus gemmatus – Jeweled Anemone Crab


Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Family: Diogenidae
Genus: Dardanus
Species: D. gemmatus

This beautiful little crab is a specialized kind of hermit crab known as an anemone crab. The frilly bits on its shell aren’t just for show – they’re a kind of sea anemone, Calliactis polypus. For the crab, the anemones provide protection. Their painful stinging cells make the crab’s predators think twice about what they snack on. Those pretty pink strands are actually specialized stinging threads called acontia which help protect both the anemone and the crab. In turn, the crab provides the anemones with movement, thus granting them access to better food resources. This kind of you-pat-my-back-I’ll-pat-yours relationship is what is known in as symbiosis or mututalism.

Dolabella auricularia – Wedge or Eared Sea Hare



Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Family: Aplysiidae
Genus: Dolabella
Species: D. auricularia

Ok, so you can’t really see the sea hare in these pictures. But you can see what it produces when it’s scared – a thick batch of bright purple slime! Sea hares – also known as sea slugs – are relatives of snails and other shelled animals, but like slugs on land, they haven’t had a shell for millions of years, thus making them more vulnerable to predators. But the sea hares aren’t defenseless, as you can see from the goo in the pictures. When they feel threatened, they are able to produce large amounts of a thick slime which confuses their would-be predator, allowing the slug to slither away unharmed. The purple color for the slime from the red algae the hares feed on.

Echidna nebulosa – Snowflake Moray


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anguilliformes
Family: Muraenidae
Genus: Echidna
Species: E. nebulosa

Tide pools are important nursery habitats, even for active predators like this snowflake moray. These scary hunters can grow up to 3 feet long and pack one heck of a bite, but this young eel is as vulnurable to predators as other small fish. The tide pools provide him and other young fish a place free of large predators where they can grow large enough to try and make it on their own on the exposed reefs. Snowflake morays don’t often eat fish, though they will if the opportunity arises. Their teeth are flatter than other species of eel, and are more suited to crushing shelled prey items like as shrimps, crabs, and sea urchins.

Octopus cyanea – Day Octopus



Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Octopoda
Family: Octopodidae
Genus: Octopus
Species: O. cyanea

By far one of the kid’s favorite finds was this small day octopus. Popular here in Hawaii as a food item (known as tako), day octopus are heavily fished. As daytime hunters, day octupus have incredible camouflage abilities. Let me point out that the two photos above are of the same octopus – those color differences are just a couple of the wide variety of elaborate color patterns and skin textures that the octopus displayed in our short time with it. Octopus have complex brains with a highly developed nervous system capable of changing their skin almost instantly as they move over different substrates. Roger Hanlon, an octopus biologist, once recorded a single day octopus changing patterns 1,000 times over a 7 hour period!

Scorpaenopsis diabolus – Devil Scorpionfish


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Scorpaeniformes
Family: Scorpaenidae
Genus: Scorpaenopsis
Species: S. diabolus

Last but not least, however, was by far my favorite catch of the week – this small devil scorpionfish, now named Stumpy. You see, this guy is one of the species that I study. I’m investigating the toxins in the entire order to get a better understanding of how toxins evolved in fish, and this little cutie is one of the many fishes whose spines possess a potent and painful sting. It’s easy to see why this particular species might be mistaken for a rock covered in algae. Because of exceptional camouflage, scorpionfish like this one are often unnoticed by tide pool goers, swimmers and divers until it’s too late and they find out the hard way exactly how strong the toxins they produce are. My goal is to better understand why other member of the order – groupers, for example – aren’t as toxic, even though they possess the ability to produce a similar protein toxin. Do they not express it? Or is the toxin itself altered to be less painful? Given that the toxins have strong effects on our bodies, it’s possible they may provide clues to new drugs or insights into how our cells work.

Stumpy here has come back with me so I can study his toxins as a part of my dissertation research. He currently resides in a tank at my house, where he has been eating like a glutton all week. The speed with which these ambush predators gulp a fish right out of the water never ceases to amaze me. Other cool fact: he glows orange in UV light. Yeah. Orange. How neat is that? I study the coolest animals EVER.

Check out more photos from this year’s tide walks on Facebook!

Christie Wilcox About the Author: Christie Wilcox is a science writer and blogger who moonlights as a PhD student in Cell and Molecular Biology at the University of Hawaii. Follow on Google+. Follow on Twitter @NerdyChristie.

The views expressed are those of the author and are not necessarily those of Scientific American.

Rights & Permissions

Comments 5 Comments

Add Comment
  1. 1. pknoepfler 3:30 pm 05/3/2012

    I love tide pools and Hawaii, but have never done a tide walk there. What amazing creatures. In Washington State where I’ve mainly done tide walks we don’t have quite so cool creatures, but still can be fascinating.
    Can you tell us more about Stumpy’s toxins? What kind of protein molecules are they? Could they have therapeutic properties?
    Thanks, Christie

    Link to this
  2. 2. Christie Wilcox in reply to Christie Wilcox 3:45 pm 05/3/2012

    I will certainly tell my readers a lot more about Stumpy’s toxins in time :) . Right now, we know that scorpaeniforms produce a large, multi-subunit protein toxin which has potent cardiovascular effects. It is known to affect muscle contraction and heart rate, relax blood vessels and induce extreme pain. The toxin it also is a potent cytolysin, or cell-killer. The protein may be capable of teaming up with others to form pores in cells, causing them to burst, leading to the edema often associated with stings. At low doses, though, toxins from scorpionfish relatives have shown anticancer activity. Truth is, we don’t really understand that much about Stumpy’s toxins. There is no crystal structure for the protein, and we’ve only isolated the sequence for it from species of stonefish. Part of my goal is to obtain and compare sequences across a diverse set of scorpaeniform fishes to look for patterns in sequence between toxic lineages.

    Link to this
  3. 3. pknoepfler 6:52 pm 05/3/2012

    Sounds like a great project. I’ll stay tuned for more.

    Link to this
  4. 4. waywardbiologist 12:48 am 05/4/2012

    Hi Christie, cool article! How do you figure out what is safe to touch and what isn’t? Is there any risk to picking up a nudibranch, sea hare, or day octopus?

    Link to this
  5. 5. Christie Wilcox in reply to Christie Wilcox 7:14 pm 05/4/2012

    A book or two on local animals goes a long way. Some species can possess toxins, so its definitely good to know what to watch out for in your area. Here in Hawaii, the major dangerous animals you might find in a tide pool are scorpionfishes, cone snails, sea urchins and maybe eels because they bite if you get too close to one. The octopus is harmless, though if he wanted to bite me it wouldn’t be terribly comfortable – but other species here, like the night octopus, have a more potent bite. The sea hares are generally harmless, and most nudibranchs are poisonous but not venomous. Some species, though, feed on anemones and other cnidarians and can recycle the stinging cells for defense, so it’s best to know what species you are dealing with.

    Link to this

Add a Comment
You must sign in or register as a member to submit a comment.

More from Scientific American

Email this Article