Echinodermata! Starfish! Sea Urchins! Sea Cucumbers! Stone Lillies! Feather Stars! Blastozoans! Sea Daisies!
Marine invertebrates found throughout the world's oceans with a rich and ancient fossil legacy. Their biology and evolution includes a wide range of crazy and wonderful things. Let me share those things with YOU!
I am continuing my ongoing blogs from Paris for the next month or so, where I am working at the Museum national d'Histoire naturelle! When one thinks of Paris, one envisions all sorts of exotic and wonderous experiences- postcards, people, exotic burlesque shows, and food... From the perspective of a biologist, the museum in Paris is EQUALLY exotic!
Why? Because the Paris museum (the French equivalent to the Smithsonian's National Museum of Natural History) receives MANY specimens from exotic, deep-sea locales around the world.
Because I don't typically get access to many of these specimens, I thought I would share some choice samples from the collections with all of you..
How exotic are these?
Well, to start-I'm not entirely certain that everything I'm showing you below has actually been described in the scientific literature... MANY new species await discovery in the French vaults..
Goniocidaris from deep-sea habitats in the tropical Indo-Pacific..
The most obvious feature here being the bizarrely shaped spines that look like big inverted umbrellas!
A second species of Goniocidaris (also from the deep-sea Indo-Pacific)
Instead of the large spines ending in big flattened horn-thing, these spines are lance-shaped and have a progression of smaller and smaller spines and flanges..
What do the unusual spine shapes do? How are they adaptive? Defensive? Reproductive?
Here's a big, deep-sea sea urchin the size of a pumpkin called Echinus melo! Another large animal that we know practically nothing about... And finally, we end with one of the more exotic sand dollars.. a genus called Rotula from the African coast in the tropical Atlantic..
Weird are the many strange flanges and holes! What do they do?
and just for kicks..here's the bottom or ORAL SURFACE of one.. yes-even these weirdly shaped sand dollars have the tiny, "fur-like" spines covering them and with the channels that lead to the mouth... More next week...as Echinoblog in Paris continues!
Caught this funky spray painted art on the streets of Paris... Is it the flapjack octopus Opisthoteuthis? (Grimpoteuthis?)
Futurama character Zoidberg? A pink crocheted Cthulhu?? (who lies dreaming in his house at the bottom of the sea..) You decide.(thanks to Allison G, John W., and Ken V. for their suggestions-even if I didn't use all of them)
A fine, beautiful foggy morning in the Jardin des Plantes. A wonderful timeless place that almost seems like you could see some great historical figures, like d'Orbigny or Lamarck still walking around in wigs and tights ... They have giant sea-urchin inspired object d'art lying around!
Their famous rows of perfectly ordered trees...a haven for kissing couples, joggers, hurried museum scientists and many, many school groups doing assignments as they hurry to the Grand Galerie d'Evolution!
Here's a statue I missed the last time I was in Paris.
Jean Baptiste LAMARCK!! On the base of the statue reads " Fondateur de la Doctrine de l' Evolution" which alludes to the more general concept of "change with descent" as opposed to Darwin's Natural Selection. Plenty to read about Lamarck here.
My business? brings me to one of the largest collections of natural history specimens in the world in an underground specimen vault known as the Zootheque-which is basically the French parallel to the Smithsonian's NMNH natural history collections..
The collections lie underground and securely sequestered away... with many buckets full of specimens, both old and new to explore...
"Secrets...." But, you don't come to Paris without taking in some of the sights...
the delightful gate at St. Denis.. the gorgeous architecture but I've always been more of a fan of the subtle, street level art. For example there's literally 1000s of these "Space Invaders" by artist Invader located throughout Paris (and indeed the world). There's even a Wikipedia page about them..
There's this pink skeleton which is part of "Gaz"Art that uses manhole covers+grafitti... A website of other examples is here. and of course, you cannot escape without pictures of French cakes!
They were such strange beasts that it was difficult to reconcile that they could possibly believe that they were alive.. here is some neat video of one that turned up recently! Just to give you some frame of reference as to how weird and hard to encounter they are...
Even most scientists that study sea urchins have probably not seen these alive!
And now, thanks to "mvardaro" and the Smith Lab (formerly at UCSD) this video is available on Youtube. Amazing.
How does the posture help? Does it assist in optimal fertilization? Why don't all species assume the posture?
Its worth noting that even though a lot of the YouTube descriptions say they are "males releasing sperm" the truth is that there's no way to sex sea cucumbers from external appearance (that I know of).
So, what you're seeing below is either eggs OR sperm. I.e., gametes or reproductive cells are being produced...by either males OR females..
hmm..this one might be interpreted badly if you have a smutty mind..
Sea Cucumbers are known by many names! Including "teatfish" aka "sandfish" aka trepang and beche de mer and probably a bunch more if I looked around more.
These are all common names for members of the class Holothuroidea or the holothuroids (the group which also includes sea pigs!)
Sea cucumbers are unusual and interesting for many reasons-but probably one of the most important reasons that people study them today is because of ALL the echinoderms, these are probably the MOST heavily harvested for food!
While they seem unpalatable, sea cucumber is a HUGE global industry and as we'll see, one that is quite important.
I'll warn ya' right now, Purcell et al's paper was fairly long. I've outlined some interesting points below-but there's much more depth to the picture..
What We Know about Sea Cucumber Fisheries (in general)
With the general decline of "fin fish" fisheries (e.,g proper fish) there's been a general increase in invertebrate fisheries.
Here we see a graphic from their Fig. 1 that shows how sea cucumber fisheries in terms of dried metric tons has grown over the last 60 years or so..
(Figure 1 from Purcell et al. 2011)
Aquaculture has only emerged recently.. we see the sea cucumber fishery jump immensely in the last 20 years. Some interesting factoids:
Throughout the world, 66 species of sea cucumbers are commonly exploited
Sea cucumbers have been, historically been fished for a VERY long time. Chinese consumption dates back at least 400 years!
Sea cucumber fisheries are presently being undertaken in some 70 countries from all the world's oceans!
Sea cucumberfisheries are focused on primarily shallow-water tropical species. Often, multiple species in a particular region are fished.
Some 20,000 metric tons have been taken in the last few years.
Why Understanding Sea Cucumber Fisheries are Important
Sea cucumbers are often dismissed as sort of the marine version of earthworms. But if you stop and think about it-earthworms are pretty important.
By extension, the diversity of animals that make a home out of those sea grass beds are affected by what sea cucumbers do. Thus, even if hypothetically, sea cucumbers were not directly relevant to fisheries or related activity-their indirect presence would still be important.
Managing Sea Cucumbers is a Challenge
So, we know they are important. Wouldn't raising them in farms be easy? How could something that looks like a giant dirt-eating log possibly be complicated?
As it turns out, we know very little about sea cucumber life cycles and on top of that all of the conventional means and assumptions that biologists use to study normal fish are not always effective.
For example, its quite difficult to actually tell how old a sea cucumber is. Growth rates can be variable and in fact, adults can shrink in size!
A common tactic-tagging juvenile fish to observe as they grow to adults-is often ineffective in sea cucumbers owing to their soft-bodies.
And finally, reproduction and replacement of the population is thought to be a complicated business in sea cucumbers. Realize that an "adult" animal may take 10 to 25 years to mature.
Reproduction in these guys is often accomplished when a significant number of OTHER individuals is either nearby or perceived by the animal as being nearby. Perhaps triggering this sort of behavior where ALL of the individuals simultaneously release their eggs and sperm!
A rash fishing expedition could conceivably wipe out a local population of sea cucumbers pretty decisively.
Fisheries Status. How bad is it? Purcell et al's Figure 2 lays out the status of fisheries around the world in this nice color graph with red indicating where the stocks of sea cucumbers have collapsed. It was not encouraging..
(Figure 2 from Purcell et al., 2011)
The authors describe the situation:
Our global analysis revealed an alarmingly high incidence of over-exploitation and depletion of sea cucumber stocks, particularly in the Indo-Pacific (Fig. 2). Over 20 percent of fisheries were depleted and 38 percent were over-exploited. 14 percent of the fisheries were fully exploited with no potential room for further expansion. Only 27 percent of global fisheries were underexplotied or moderately exploited and many of these were in deeper, temperate waters or the fisheries were in moratoria hiatus or developmental phases.
Who Fishes for Sea Cucumbers?An important dynamic to understanding the sea cucumber fishery is to look at WHO fishes for sea cucumbers ! Some factoids:
The majority of sea cucumber fisheries (66%) involved small-scale fishing operations for export (as indicated in their Fig. 3 below). The yellow indicates fishing operations limited to individuals and single boats and so forth.. As you can see-relatively few are actually at a well-developed industrial level.
Most of the exploited species are tropical, shall0w water species. Often abundant and easy to obtain.
Some 27% of the fisheries operate illegally-operating despite national regulations controlling the fishery.
Many of the aforementioned small scale fisheries occur in countries with low per capita income.
Several of those countries occur throughout the Indian and Pacific oceans and are located in areas with an unusually high diversity of sea cucumber species. Some regions will take anywhere from 20 to 47 different species as part of their fishery! (see their Fig. 4 below). In contrast, maybe 4 species are taken from Central and South America.
Diversity in several of these areas remains, in many cases, poorly known.
Fishing for Sea Cucumbers is something that is performed by a wide range of individuals ranging from women and children to more sophisiticated fishing outfits.
Here is a video that illustrates some of the practices.. The cucumbers processed and then are sold to higher level dealers who then export the materials from the home country typically to Asia.
Some 2 million individuals have been engaged in collecting sea cucumbers from 39 of the 77 fisheries that were examined! The authors estimate that some 3 MILLION people collect sea cucumbers worldwide-either full or part time. Among the countries with the highest number of individuals fishing were:
The Philippines (37.4%=some 930,000 individuals)
Papua New Guinea (18.1%=some 250,000 individuals)
Indonesia (15.9%=810,000 individuals)
What the Future Holds
The authors state in their Discussion:
Our analysis shows that sea cucumber fisheries fare worse than most fisheries globally. We found that 58% of sea cucumber fisheries were over-exploited or depleted, whereas 27% of global stocks (finfish and invertebrates) were over-exploited or depleted over the same period.
Many sea cucumber species face a high risk of extinction through overfishing coupled with inherent biological and ecological vulnerability.
Apart from an unlikely reduction in demand from Chinese consumers, we believe that sustainability and resilience of troubled sea cucumber fisheries will only come from the adoption of radically different approaches to management.
The authors also emphasize that regulation and ultimately enforcement are among the most important tools that can be applied to the sea cucumber fishery.
It was also worth noting that sea cucumber fisheries were heavily relied upon in low-income countries for "poverty reduction and/or subsistence diets".
Purcell et al.'s data showed that these countries tended to experience overfishing MUCH more than those in high-income countries.
This has led the authors to hypothesize that the crash of these fisheries is likely a confluence of:
1. ease of sea cucumber collection
2. and biological and ecological vulnerability (growth, reproduction, etc.) So...the future for sea cucumber fisheries seems bleak But Purcell et al remained insistent that management and especially INVOLVEMENT was crucial to the ongoing maintenance of sea cucumbers as a fishery...
Last week, the Echinoblog Mail Dept. received a great letter (a REAL paper letter!) from an aspiring young person with questions about STARFISH!
Her name is Brianne (name changed to protect privacy) and she's an intrepid 6th grader from an elementary school somewhere in Colorado!
Her teacher, JH is applauded for encouraging her to write me the letter and for fostering Brianne's interest in science!
Her letter read as follows (corrected for spelling..)
Our teachers asked us students to write to an expert on a topic, that we chose, and I chose to write mine on starfish. I chose starfish cause starfish are just a mystery; I want to learn more about starfish.
I'm looking forward for your response on starfish, on the questions. Thank you I knew you were the right one to write to.
Thank you Brianne!
First-let me make sure that you understand that when I say "starfish" this is a different word that describes the same animal as "sea star"(Class Asteroidea in the Phylum Echinodermata) and just so that we are clear, a starfish/sea star is NOT a fish in the same way that say, a goldfish is a fish.
Starfish belong to a group of weird spiny-skinned animals called ECHINODERMS. Which includes starfish, sea urchins and all of their relatives!
Brianne's questions follow.... (some questions were related and these have been grouped together)
1. How do starfish eat?
There are many ways that starfish eat. But most of them feed by extending their stomach out THROUGH their mouth and onto whatever they happen to be feeding on.
Food might be anything from organic slime to algae to animals that either don't move very much(such as mussels or clams) or may never move (such as sponges). Some, as we'll see below are fierce predators.
This video shows a small bat star under high speed so that you can see it moving!
Do you notice that kind of brownish colored jelly that seems to grow and than shrink? That is the stomach extending through the mouth and onto the surface of the clear glass aquarium!
2. Do starfish bite?/Do Starfish have teeth? No and Yes.
This will seems strange at first... starfish do not bite! But SOME starfish DO have teeth!
Since most starfish feed using their stomachs, there's no real need for them to bite and chew the same way that say, a dog might.
BUT there are some starfish that have a lot of spines located around their mouth that might be important to helping them eat. See those red circles below? Those are indicating spines present on a few special species that like to eat a particular kind of sea sponge. They aren't for chewing but they might be important for eating in ways that don't know much about yet.
For the sake of being clear, let me say that starfish do NOT BITE. You don't ever have to worry about a starfish ever hurting you in that way. They may have teeth and a stomach-but they don't really have jaws....
3. Can starfish live on shore? Yes (kind of..)
Most starfish species live at depths where they are always underwater, but there are many species that live right at the edge of the ocean but most do not live exactly on the sandy beaches (although some do live near sandy beaches! and become easier to see when the tide goes out)
In this video from British Columbia, you can see many examples of the colorful Ochre Star (species = Pisaster ochraceus) living where the waves crash onto the rocky reefs.
On the other hand, there are other species which live only on muddy or sandy bottoms but in very shallow places near the coast. In the United States, you are likely to find these kinds of species on the tropical Atlantic coasts of Florida and Texas.
But here for example is a video of the intertidal area in Singapore! If you move the video to the time at 3:02 there are sea stars/starfish that live in very shallow mud and sand.
4. Do starfish move? YES. absolutely they do!
However to a human being's eyes-they move VERY slowly, if at all. However, if you put a camera on them and SPEED UP the recorded motion from several hours or minutes you can see all kinds of movement and behavior!
here is an example of such movement as several bat stars move over the seafloor
Some species, such as the Sunflower sea star on the Pacific coast of the US moves so quickly that you can see them without a camera..
5. Can they swim?
ADULT starfish don't swim and live their lives, crawling around entirely on the bottom of the sea floor.
But juvenile starfish (called larvae) have a very different body shape than adults! Starfish undergo a change before they become the large adult-bottom living form in a similar way that slow-moving caterpillars transform into flying butterflies.
When starfish/sea stars are "babies" (=larvae) they look like this and are covered with many small hairs that constantly move and help the larvae to swim and move. So that one day, the larvae will settle on the bottom to become an "adult" starfish.
Larvae are VERY tiny. This one is about the size of the tip of your pencil!
In this case, the tiny larvae above, settles down and grows up into the big adult over the course of several years (almost 2 feet across!).
6. Do starfish have eyes? Yes..kind of..
Although starfish/sea stars DO have something similar to eyes, they are not quite the same. There are organs on each of the armtips that permit starfish to sense light and perhaps heat.
Many special sensors lie on the top of their body that allows them to sense light. Many species are sensitive to light and will move off if it is too hot.
Note the GREEN ARROWS below! Those are where the "eyes" (technically called eye spots) are located.
However, "seeing" is not as important to a starfish as it is to a human being. Starfish bodies are open to the sea water around them. They don't have blood like we do, they just let the ocean fill every part of their body!
Because the ocean is always "inside" them, they can "smell" or detect food immediately. They can detect anything good or bad that might be around them. This includes "smelling" bad things like poisons and uncomfortable things about the water (such as if it is freshwater -starfish only live in sea water). But they can also "smell" predators and prey immediately!
Many predators that feed on starfish can immediately be sensed by a starfish when their "smell" gets into the water. If a starfish doesn't like the smell, it will move away from it very rapidly..
7. Do starfish have gills? Yes!
Starfish breathe by absorbing oxygen from special finger-like structures that are found on their body surface.
If we enlarge the area in the blue circle to the box below...
We see all of those fuzzy patches between all of the white granules/spines. Those fuzzy patches are each a single finger shaped balloon like structure called a papula (plural is papulae). Those are the gills.
Each one of those patches can contain dozens of papulae, which are extended when the animal is comfortable and feels secure. Each of these permits the animal to collect oxygen for the starfish to breathe. They are generally found only on the top and side surfaces, generally not on the underside.
8. Are starfish mammals or do they lay eggs?
Starfish are members of the phylum Echinodermata. A phylum represents the largest natural grouping of different 'types' of animals. For example, phylum Mollusca includes squids, clams and snails and phylum Arthropoda includes insects, crabs, spiders and centipedes. Humans and mammals belong to the phylum Chordata-also called the chordates.
Echinoderms are the "spiny skinned" animals-and include starfish, their close relatives the brittle stars, sea urchins, sea cucumbers, and feather stars. Echinoderms are on the same "side" of the family tree of the animals but are quite distant from chordates (which includes the mammals). Echinoderms have evolved in a VERY different way and in a much different direction than Chordates (mammals). And so, their biology is also much different.
Their reproductive/egg-laying biology is one example of how different they are..
Here is a video of a starfish from the tropical Pacific (in southern Japan). Not all starfish assume this unusual "standing on arm tips" pose..See those white threads being released by the animal?? This species is releasing reproductive cells-called gametes into the water.
Male and female gametes join together in the water and grow into a series of different small larval stages that eventually settle out and grow into an adult.
Here is video that shows the many different stages as they grow and develop...ultimately becoming an adult.
MOST times, eggs and baby starfish form in the ocean. BUT in some UNCOMMON cases there are species of starfish that will actually KEEP their eggs or juveniles until they grow to an adult size...
Again..this is NOT typical.. but it does happen. These eggs and juveniles are usually kept around the mouth... 9. Do starfish have brains? No, but...
So, starfish have what is called radial symmetry (specifically pentaradial or five part symmetry). That is, if you were to cut the animal in half it does not have an exact and opposite side.
The arms all project out from the middle the way that spokes on a bicycle wheel project from the middle. As a result, there is no head or true central location where the nerves meet.
In its place, is what's called a radial nervous system. The nerves form a ring around the mouth in the disk and radiate out along the arms.
Although the nerves seem simple, this style of nervous system has likely been around in starfish for a very long time.
Although its not as apparently developed as the brain or nervous system in a human (or some other mammal) the behavior in sea stars is surprisingly complicated. Under time lapse cameras, biologists have observed that sea stars are capable of a great deal of behavior that one would not expect from such a seemingly simple nervous system!
Whew! Okay. that's some good questions! My thanks to Brianne and her teacher for these great questions!!
If they or any other students would like to get further clarification of if you have more questions, drop them in the comments below and I'll do my best to answer them by the end of the week! (answers will be in the comments)
I am continuing my ongoing blogs from Paris for the next month or so, where I am working at the Museum national d'Histoire naturelle!
When one thinks of Paris, one envisions all sorts of exotic and wonderous experiences- postcards, people, exotic burlesque shows, and food...
From the perspective of a biologist, the museum in Paris is EQUALLY exotic!
Another large animal that we know practically nothing about...
And finally, we end with one of the more exotic sand dollars.. a genus called Rotula from the African coast in the tropical Atlantic..
Weird are the many strange flanges and holes! What do they do?
and just for kicks..here's the bottom or ORAL SURFACE of one.. yes-even these weirdly shaped sand dollars have the tiny, "fur-like" spines covering them and with the channels that lead to the mouth...
More next week...as Echinoblog in Paris continues! 
Bonjour from Paris! As promised, blogging for the next few weeks from France at one of the greatest museums in the world!
Here's a statue I missed the last time I was in Paris.
But, you don't come to Paris without taking in some of the sights...
There's this pink skeleton which is part of "Gaz"Art that uses manhole covers+grafitti... 
