Tag Archive: ocean

shrimp goby

A shrimp goby guarding the opening of a shared burrow. Image taken at the California Academy of Sciences.

Most of the time if you see a shrimp goby, you’ll find it keeping watch with its tail in a burrow, just like the one pictured above.  But every once in a while, you might catch something else peeking out of the burrow, and that’s the shrimp goby’s partner, a shrimp.  This shrimp will not venture very far from its goby partner, because the shrimp needs its goby and the goby needs its shrimp.

goby and shrimp

A shrimp goby with its crustacean companion. Image taken at the California Academy of Sciences.

There are many different species of goby fish and shrimp that have this partnership, but in general they have a few things in common.  Usually, the shrimp digs and maintains the burrow.  The fish in turn acts as a look out, as the shrimp has really poor vision. At least one of the shrimp’s antennae will keep physical contact with the fish at all times.  The fish will flick its tail to alert the shrimp of any danger and they will both hastily retreat into their burrow.  With some species, studies have shown that the shrimp stops digging burrows and growing if it doesn’t have a seeing-eye fish and the gobys get eaten up quickly without a shrimp to dig and reinforce the burrow.

If you want more information on this special relationship, check out this site by the University of Hawaii’s goby researcher, Rob Nelson. I especially recommend the section where he discusses the studies done on how the shrimp and the fish find each other.


False Clownfish: AKA the Nemo fish

Clownfish in anemone

False clownfish in anemone. Image taken at the California Academy of Sciences.

I’m a big fan of the movie Finding Nemo, so the first fish on my blog is Nemo, AKA the false clownfish.  In the picture above, Nemo is carefully tending to his home anemone. In general, false clownfish live in groups with one dominant female, which is the largest fish, a dominant male (the second largest) and then a few male underlings. Just like in the movie, they seldom stray far from the protective arms of the anemone, which is also where they lay their eggs. They will care for their eggs by fanning and guarding them. There’s a lot more to the relationship between Nemo and the anemone, but I will discuss that in depth in a later post.

So the movie certainly got some things right about the life of an anemonefish. However, it did miss one important part of their life history. (Yes, I know it’s a cartoon. What’s your point?) Anyway, in the movie, you might recall that Nemo has a dad but he doesn’t have a mom. But in real life, this would never happen because Nemo, like all false clownfish, is a sex-changing fish. So in real life, if Nemo’s mom died, then Nemo’s dad would turn into Nemo’s mom.  Maybe they’ll make a part 2 and Marlin will be Marla! Yeah, okay, probably not, but my inner nerd loves the thought of scientifically accurate cartoons.

BTW, one thing that’s seriously hurting Nemo’s home in the coral reef right now is that a lot of people like to have brightly colored tropical fish for their home aquariums, and divers don’t always use environmentally friendly ways of getting these fish.  They use dynamite and poisons, for example, to stun the fish to collect them. So, if you’re considering a Nemo for your home aquarium, you can help by asking if your Nemo was raised in captivity and avoiding Nemos that came from the wild.

Nudibranchs: The Sea Slugs

sea slug
Image taken at Aquarium of the Bay in San Francisco

The world of sea slugs is an amazing one.  First off, they are absolutely, stunningly gorgeous.  The one pictured above is comparatively subtle, with its pretty frosty spots, but sea slugs come in every color of the rainbow with fantastic and startling features.  Check it out, right now.  Go on.  Google image nudibranch and see what fascinating creatures pop up.  I’ll wait…

Finished?  Told you so.  Alright, so these animals are beautiful.  But they are even beautiful as eggs.  That’s right, they lay their eggs in gorgeous ribbons that look to me like underwater flowers.

egg ribbon
Sea slug egg ribbon.  Image taken at Aquarium of the Bay.

But beauty is not the reason why sea slugs are my favorite animals in the ocean.  No, that would be because of the multitude of ways these animals have to defend themselves.  So imagine for a moment that you decided that a porcupine would make a tasty treat.  You caught a porcupine and ate it.  And then all of a sudden you grow quills out of your back.  It’s absolutely absurd I know, but sea slugs do something similar.  Some species of sea slug eat sea anemones, which are animals that are related to jellyfish and like jellyfish, they have stinging cells called nematocysts.  (See a video of nematocysts firing here.) But the sea slugs don’t get stung by their prey.  No, instead as they make a meal of the anemone, the stinging cells pass through their system undischarged and then pop out of their back, so that the nudibranch has now essentially stolen its prey’s defenses to protect itself.

Other species of sea slug eat sponges instead.  Sponges are animals that are often poisonous, but the sea slug is not at all deterred by the toxins in their prey.  Once again, they will steal their prey’s defenses and instead of being poisoned, they will store their prey’s toxins and become poisonous.  Sponges are also often brightly colored, a warning to other organisms that they should be left alone.  When a sea slug eats its sponge prey, it will not only take their toxins, but it will steal their pigments as well, so when they are on their host sponge, they will be perfectly camouflaged and when they move away, they will exhibit wonderful, bright warning colorations.

Last, but not least, there are at least 2 species of sea slug that are pelagic, which means they float in the water column instead of crawl on the bottom of the sea floor.  One of these species actually eats the portuguese-man- of-war, a highly venomous animal (or rather, 4 types of animals working together) that is also related to jellyfish.  Pretty impressive, huh?

And I didn’t even get into the regenerating sea slugs or the sea slug that can photosynthesize!!  That’s right, the first animal ever found that can make food using only sunlight, like a plant.  (Note that it is not simply storing algae in its body and stealing the food the algae is making.  This is true photosynthesis.)

If you’re interested in learning more about sea slugs, the Australian Museum has this wonderful forum to start you off.