Category Archives: Cnidarians, Hydrozoans, and Sponges


Fans of the Hitchhiker’s Guide to the Galaxy will remember Slartibartfast, the planet architect who was very proud of his award-winning design for Norway. The fjords, he explained, were designed to give the continent a “baroque” feel. And a fjord is indeed a very splendid thing. A fjord, by definition, is a long and narrow inlet to the sea, flanked by very steep cliffs, and carved by glacial activity. (Or Slartibartfast.) While Norway coined the name “fjord,” they have no trademark on the geological flourish. You will find fjords anywhere there are mountains that meet the sea, and freezing temperatures to support glaciers, including the coast of Chile, New Zealand, and the Northwest coast of North America.

First Prize!

From time to time I like to take electronic expeditions to rare places on Earth, to see what I can find. Readers know I have a passion for fractals, and subscribe to something I call Fractal Earth Theory; the theory that the patterns of the planet are self-repeating ad infinitum. It was thinking about the true lengths of coastlines that led Mandelbrot to discover fractals in the first place; fjords make for rough edges in the world, wrinkling the land into a series of nooks and hidey-holes in which any manner of animal might live.

Today, we look for the unique wildlife of the fjords. I use a basic set of hypotheses as a compass:

1. Wherever life can exist, life will exist.
2. Where ever a habitat is geographically separated in any physical way, unique life will exist.
3. The more severely isolated a habitat is, the greater the number of unique species.

Fjords, however unique as geologic structures, are not very isolated: their cliffs connect with the mainland, and their inlets connect with the ocean. Their main aspects of geographic distinguishment are the steep angles of their cliffs, on which only certain wildflowers can grow, and the murky, silty, brackish water below. Fjords are often estuarine, with freshwater running as a river into their channels, which will certainly exclude many sensitive saltwater animals. The turbid, murky water is caused by violent tidal action, which in turn is caused by the water rushing over the lip of the terminal moraine left by the glacier at the fjord’s edge; this turbulence may also make the habitat even more exclusive, and more unique. But all in all, a fjord is not as isolated as a lake or an island, and we can’t expect a great number of unique species. But a few, sure. Some modifiers to the original compass:

4. The cold temperatures and low salinity will lead to a lower general biodiversity for animals, compared to a tropical habitat.
5. The cold water, with its high level of dissolved oxygen, will nonetheless support a high overall biomass.
6. The prediction of high aquatic biomass makes it more likely that any unique species are aquatic.

With these in mind, we set out to explore the nooks of the fjords, seeking life found nowhere else on Earth. And what we’ll find is a series of ecosystems among the most mysterious and little-known in science.

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Hey Kid, Want A Lollipop?

It looks like an avant-garde light fixture. Or perhaps a frozen firework. It is, in fact, the recently-discovered Ping-Pong Tree Sponge, a carnivorous sponge found in the deep waters around Monterey Bay.

Roll that phrase around in your mouth for a minute: “carnivorous sponge.” Most sponges are sessile, simple animals lacking any respiratory, circulatory, digestive or excretory system of their own. Instead, they let seawater do all the work for them. With no blood and almost no organs, eating whatever plankton happens to flow through them, their living tissue is merely cobwebbed into a scaffolding of silica. It is as if the animal is barely there at all.

THIS sponge, on the other hand, is free-floating, and uses its hydraulic water system to puff up its intriguing balloon-like appendages. Each one is laced with silica hooks, perfect for catching minute crustaceans. When it snags one, its “eating” cells migrate to the balloon that’s caught the food, and dissolve it. It’s a perfectly geometric predator. In some ways, it reminds me of the carnivorous sundew plant, which attracts insects to its lollipop-like lures, where they become stuck and then digested. Something about brainless carnivores with mouths on all sides gives me the willies, in a good way.


I like to start each day by drinking a nice hot mug of cobra venom.

Did I say cobra venom? I meant coffee. But if I wanted to, I could certainly drink cobra venom, provided I didn’t have any cuts in my mouth or esophagus. I offer this as an example of one of the many ways that “venom” is not synonymous with “poison.” A poison can be anything that harms the body, from complex organic compounds to heavy metals to atomic radiation to bleach under the kitchen sink. But venom is special. Venom is an arrangement of proteins and enzymes that must be injected into a victim’s bloodstream through a mechanical device, such as a fang. Poisons are land mines that anyone can step on; venoms are delivered special to you.

Most of the venomous animals in the world are snakes, but there are a fair number of fish and lizards that deal death as well. The stonefish, the world’s most venomous fish, uses spines to defend itself against attackers, and can certainly kill a human, and gila monsters, one of two North American venomous lizards, produce a neurotoxin which cause an excruciatingly painful paralysis. The world’s most venomous land snake, Australia’s Inland Taipan, has never killed a human due to its reclusiveness, but the venom in one bite is powerful enough to kill 100 people. A few molluscs make the list: the golf ball-sized blue-ringed octopus — again, Australian — has a blinding, paralyzing toxin that will kill a human victim in minutes, and for which there is no antivenin. The venom is nearly identical to that of the marbled cone snail, nicknamed the “cigarette snail” because you’ve got about enough time left on Earth for one cigarette after it stabs you with its neurotoxin-tipped harpoon. But the most venomous animal in the world is the infamous box jelly, the “suckerpunch of the sea,” a nearly-invisible predator responsible for over 5,500 human deaths since 1954. Of course, its fatal deathblow usually comes from the drowning triggered by extreme pain before the venom can stop the victim’s heart.

Clearly, venoms are useful to predators across the animal kingdom: reptiles, fish, insects, cnidarians, molluscs, and even a few amphibians. Why, then, aren’t more animals venomous? And why aren’t there any venomous mammals? And here is where a few of you zoophiles say, What about the duck-billed platypus? Very good; just testing you. The male duckbilled platypus, and only the male, has venomous spurs on its hind legs. The few other venomous mammals are all types of shrew, including one of the rarest and strangest: the solenodon.

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Then Jesus asked him, “Why is thy name?” And he replied, “My name is Legion, for we are many.” Gospel of Mark 5:9

Yesterday, I mentioned a hydrozoan called the By-The-Wind Sailor. Today we honor another favorite prey of the Violet Sea Snail, and one of most fearsome animals in the ocean: the Portuguese Man O’ War. In fact, it does it an injustice to call it an animal. It’s actually several thousand animals, comprised of four different types of animal.

What? It may look like a sea jelly, and sting like a sea jelly. And it is closely related, in the Cnidaria family. But there are a few key differences between a jelly (Scyphozoa) and a hydrozoan like the Man O’ War. This drifting beastie is actually a siphonophore, a colony of smaller animals called zooids that merge to become one organism. “Like Voltron!,” you say. Sort of. The difference is that the zooids are highly specialized to their tasks and cannot survive without each other, whereas awesome giant robot spaceship lions, when separated, are still awesome giant robot spaceship lions.

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After yesterday’s post about indigo animals, I thought I’d write about my favorite violet one.

Meet Janthina, the violet sea snail. It lives at the surface of the ocean, where it preys on jellyfish and hydrozoans, particularly Velella, the By-The-Wind Sailor. Unlike Velella, which rides the surface of the waves from above, Janthina rides the surface from below, on a raft of bubbles encased in tough chitin, like Huckleberry Finn through the looking-glass.

For the violet sea snail, up is down. The sky is its floor. Its prey lives underground, in the air. Floating along at the mercy of the current and the storms, it has no concept of terra firma, yet is rooted to a surface in all weather. That surface is the same we row our boats in, yet opposite. When you need some perspective – emotional or scientific – think of the violet sea snail, and you’ll remember that every “in” is an “out” door, every window looks both ways, every floor is a ceiling. And every floor is also your shadow’s floor, and that life walks with you in mirror-image, upside-down in your footsteps.

Forever Jelly

Friday we talked about the world’s oldest organisms. Today, I can do you one better.

Turritopsis nutricula is a hydrozoan, very closely related to a sea jelly. Jellies and hydrozoans have two distinct stages to their life cycles. The jellyfish we all know and love is the mature, sexual medusa stage. But that jelly spent the first part of its life as a tiny, asexual polyp animal stuck to a rock, like a miniature anemone. That polyp grew into a strobila, grew stacks, like a Japanese pagoda, and the levels of those stacks eventually popped off and became baby medusas. But that strobila will continue living, popping off new jellyfish, until something licks it off its rock. So while an adult jellyfish has many cloned brother/sisters, it is not a clone of its strobila; it is its strobila. It’s the free-swimming extension of its strobila. The jellyfish is living in many different bodies, with two different forms, all over the world’s oceans, at the same time.

But I blow your mind digress. Turritopsis nutricula isn’t content to just live in several different bodies at once. It is unique, in that it can regress from its mature medusa stage to its larval strobila stage all by itself, and grow up all over again. And it can repeat this trick indefinitely. This means Turritopsis nutricula isn’t just long-living.

It’s potentially immortal.

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Are there creatures who can use their beauty to devastate, or to defeat a threat?

Well, what is “beauty”? If it has any aesthetic sense at all, a male blobfish probably thinks a female blobfish is the prettiest thing in the sea. But I’d like to think that a doomed fawn can find an approaching tiger beautiful, and terrifyingly so. And perhaps a stag is beautiful to other stags, if mostly because it makes a fearsome impression. So you could say that beauty is an outward expression of health and strength, to attract mates or intimidate rivals. If it has components, you could say that size, color, grace, and symmetry all play a part. But in the end, it does live in the eye of the beholder.

Evolutionary psychologists who study the concept of beauty think it originated as a sense of utility. Take flowers, for example. They developed color and symmetry, nectar and aroma to lure insects. Humans almost universally find them beautiful, although they serve no immediate practical purpose to us. However, far back in our genetic memory, we might recall an artistic, sensitive caveman ancestor who fancied flowers more than the rest of his tribe, remembered where those flowers were, and was able to come back later and find the fruit those flowers became. It is my belief that the ability to appreciate beauty is a survival instinct.

Is there anything that creates beauty to survive? One example would be the cuttlefish, which can actually hypnotize prey. By flickering between different colors rapidly, or pointing their tentacles at their target and creating concentric rings of color moving up their arms, they stun their prey like an old-school mesmerist with a spiraling wheel:

But my favorite example, once again, comes from the deep sea. It’s a bioluminescent jellyfish. In the video below, you can see what it looks like with the lights on, and off.

Here’s a superpower closer to Dazzler’s, or Jubilee’s. When it bumps into something and perceives that it’s being attacked, this Alarm Jelly, Atolla wyvillei, creates a pyrotechnic light display that does two things:

1) Stuns its potential predator. Remember, to these creatures any light at all is a source of curiosity, so this must look like a visual hallelujah, stopping an animal in its tracks.

2) Illuminates the predator, while advertising that predator’s presence to bigger predators. The “alarm” jelly could also be called a “distress call” jelly. Touch it, and you’re not only no longer invisible, but everything in visual range that could eat you knows where you are. So the jelly’s beauty may not be deadly in itself, but it might just get you killed.