The Sea Urchin Skeleton as Art! Natural and Enhanced!

There is a natural and wonderful symmetry to many natural objects and echinoderms have always had a certain appeal to folks with artistic natures. Their skeletons are pentameral and often have no shortage of patterns and visually interesting processes. Go here to seem my SEM odyssey of the urchin test!

Sea urchins are no exception to this-and everyone I know who has ever found an intact sea urchin (or sand dollar) test on the beach is always delighted. A "test" is the name of a sea urchin skeleton. They don't have "shells".

Here's a nice example of a cidaroid sea urchin test. The spines attach to the "knobs" (called bosses) that are present on its surface.

sea urchin test by Rainy City

Today, I thought I would present some of the many delightful examples that many of these tests have found their way into the creative processes of the wonderful artists on the Internet!  Then compare below with some examples of sea urchin tests with their own innate artful patterns!

Cidaroid Urchins a la Warhol! by Calypso985

A stunning underlit cidaroid urchin test by Mark Bolles

A neat repeating Urchin Spiral by Jeff Kreulan 

"Red Tide" part of an art exhibit featuring urchins with a distinctive presentation. Pic by Selene Vomer

"Algae Bloom"   Image also by Selene Vomer. Chicken skeleton over urchin skeleton. Hm?

"Phosphorflock" Pic by Selene Vomer. I think its supposed to represent some kind of egg?

Here it is illuminated...

Image by tiboutoo

Illuminating or highlighting urchin tests with lights, lasers, fluorescence is a common theme...

An illuminated urchin by gmenut

One lit up with fluorescent lighting... "Voodoo Moon" by Sea Moon

"Sea Urchin Laser Fluorescence" by Bob Fosbury

And there's this stop motion classic "Javelin" by Ian McAlpin


Natural Beauty  In contrast, here's some tests in their natural glory...

a cidaroid test by gripspix1

Another urchin test. Image by "fontplaydotcom"

The test of Coelopleurus exquisitus, a recently discovered New Caledonian sea urchin species, described by my colleague Simon Coppard, who found tests of this species on Ebay a few years ago!

Amazingly, the patterns? ARE NATURALLY OCCURRING. Those are on the test under the spines and all of the other structures and skin on the surface! They don't disappear after the animal has died. They are ingrained in the mineral structure of the test.

Both images below are by Simon Coppard

and we didn't even get started on Irregular urchins like Clypeaster and the other Sand Dollars..

Strange Urchin Spines! Past and Present!

Tylocidaris clavigera from the Cretaceous of England Stunning image from the BMNH Echinoid Page. here

SEA URCHINS! Everyone kinda knows the basic idea: round spiny ball that lives in the ocean but most folks aren't as familiar with how CRAZY the spines can get. ESPECIALLY in the fossil record!

Most of these taxa are either cidaroid sea urchins or closely related to them. Cidaroids are considered a "stem group" among sea urchins. That is to say, they arise early in the evolutionary history of the group. They have a different jaw apparatus and vary in several other respects. Including the unusual absence of an epidermis from the spines, which permits growth of various other organisms on the surface. I've written about this here.  

Cidaroids may also be very important in understanding deep-sea dynamics and the historical ecology of other echinoderms, such as crinoids (feather stars). See that article here.  They have been around for quite awhile.. and have been known since the Paleozoic..

But some of the CRAZIEST urchins occur from the Mesozoic, that is during the time best known for the dinosaurs. Oceans were widespread during this time

One of these neat urchins is the Mesozoic (Jurassic to the Cretaceous) to recent cidaroid urchin, Tylocidaris.

Tylocidaris appears to have MASSIVE, club-shaped spines which were presumably used for defense..

Image of a cast by Ryan Somma

Here is some bewildering diversity of Tylocidaris spines, which all look like maces or big notched watermelons!  Presumably these were used as defense against predators.

MUCH thanks for the images from this Danish gentleman's excellent page about fossil sea urchins! 

These spines are from a Cretaceous Tylocidaris  sp.

Image by Søren Bo Andersen fr. his website

More Tylocidaris spines!

Image by Søren Bo Andersen fr. his website

 ..and still more!

Image by Søren Bo Andersen fr. his website

Interestingly, the British Museum's sea urchin website also indicates that a LIVING member of this family is still kicking around.. the unusual Psychocidaris!
Psychocidaris oshimai..

Curiously, the spines seem to be made up primarily of this weird cortex like covering...

Here's a video from a mineral/fossil show showing a bunch of fossil Tylocidaris-like urchins to a jazzy tune!

SIMILAR URCHINS...
the Jurassic Pseudocidaris mamossa Big CLUB like spines!

Image by Fernando Bravo

Asterocidaris  spp. 

And just in case you thought only fossil urchins could have all the fun! here' an assortment of neat urchins that are alive TODAY which bear bizarrely shaped spines...

But note that the spines aren't just huge and club-like.. they have all of this weird ornamentaton. What could their function be? defense? assist in reproduction somehow?

Goniocidaris sp. from the South Pacific. (MNHN Paris collection)

A second Goniocidaris species.. with very different spine patterns..

Morphology-seemingly simple and straightforward... and yet, what do the animals use them for?

Tiny Starfish hermaphrodites with live cannibal babies!

Image by Nuytsia@Tas

Data for this post was derived from Maria Byrne's 1996 paper in Marine Biology: "Viviparity and intragonadal cannibalism in the diminutive sea stars Patiriella vivipara and P. parvivipara (family Asterinidae) vol. 125: 551-567 which is a pretty neat piece of work that set the groundwork for their paper in Biology Letters which was just published today! Today's post has been reported in the news (here) .

Our story begins with an overview of two unusual and quite tiny starfish! Some details:

• Occur in Tasmania (Southern Australia) 
• Two species, Parvulastra vivipara and P. parvivipara occur on rocks and surrounding areas.
• One of those starfish, P. parvivipara is among the world's smallest adult sea stars. 

Indeed! Look how cute and tiny they are!

Image by Nuytsia@Tas

But the  truth is that these tiny little starfish have all kinds of shocking sex secrets!

1. Both Species of Parvulastra are self-fertilizing hermaphrodites. 
I have written about similar species in the same genus (Parvulastra) here. 
Yes, that's pretty much self explanatory. Individuals are simultaneously both male and female AND if need be they can fertilize themselves. 

They typically have between 6 to 8 female gonads and 1 predominantly male gonad. However the amount of sperm present would not be expected in those species which are exclusively self-fertilizers-so SOME outcrossing (ie sex with other individuals) does occur.

Image by Nuytsia@Tas

2. Parvulastra broods juvenile starfish in a brood chamber (aka "live birth" aka viviparity)
Several species of starfish are known to possess "brooding" behavior (I've written about them here). That, is the adult "carries" either internally or externally several tiny juvenile starfish with it until they are ready to move off on their own as full adults.

Each adult Parvulastra carried multiple juveniles across a range of sizes. Here was one example of a clutch containing 30 individuals from ONE large individual. Number varies with size..

scale bar= 1.0 mm, From Byrne 1996, Fig. 4e

These further images from Byrne's paper give you an idea of where they are located. Essentially throughout the body cavity between gonads. This differs from other species which can have them living around the mouth or in other locations.

From Byrne 1996, Fig. 4a

So, eventually, those little baby starfishes have to leave the comfort of the mother's body cavity. This happens when they reach about 25-30% of the parent's body diameter.

The downside of having brooded juveniles is that they tend not to go very far from the adult. In other species, the larvae would be dispersed over wide distances but here, they are retained or crawl away, staying near the parent.. 

Eventually, they exit via openings in the abactinal body wall called GONOPORES. 

But what motivates the exit? 

3. Those juvenile starfish are cannibals! (aka intragonadal cannibalism)

Life is harsh and these starfish know it better than anyone. The gonads in these animals are pretty small which implies that food for the juveniles isn't really enough to keep them sustained on their own..

So, as soon as the brooded juveniles develop a mouth they begin feeding on their siblings in the body cavity! In the specimens examined several of the larger brood individuals, which contained traces of the smaller ones in their gut contents in addition to other observations..

Several possible reasons may motivate the departure of the smaller juveniles from the brood space. Temperature or any number of factors.

Byrne speculated on one reason that juveniles may vacate in order to avoid being fed upon by their larger siblings.. Here is a cartoon supplied by the Echinoblog Art Dept. which illustrates this notion (which to be honest was mentioned as only one sentence by Byrne in her paper).

Thus starfish join the illustrious ranks of those animals which have active, intrachamber type young which feed on one another including sharks, fishes and salamanders and insects-although there's a bunch more..

4. Exit to the Outside World! 

Ultimately, then we see various brooded juveniles vacating the brood space via the gonopores (which flex and open) with the tiny juveniles emerging on the surface and eventually moving away...

Fr. Byrne 1996, Fig. 8b

Thanks to the intragonadal cannibalism however, sometimes you get a REALLY big one which continues to grow INSIDE the parent.  Ultimately reaching a size at which it cannot physically escape on its own..  

Yikes! Talk about living in your parent's basement! 

From Byrne 1996, Fig. 4h

5. Reproductive Impact on Populations

As indicated above, a recent paper by Carson Keever and others has found some significant drawbacks that this unusual reproductive behavior will have on populations of Parvulastra.

• Self-fertilization by hermaphroditic adults and brooding behavior causes strong inbreeding and "genetic poverty"
• There was nearly a complete loss of genetic diversity among all populations of Parvulastra and given the very restricted geographic range of these species+ the very limited way they can disperse their juveniles across wide distances there's little potential for populations to expand.
• Thus, these live-brooding species with little to no gene flow display a high risk of extinction

So, there is serious concern about these species to withstand any kind of temperature or climate shift. The populations of these live-bearing starfish species is pretty small and pretty restricted. Potentially any kind of abrupt habitat change could wipe out these starfish with these unusual life modes..

Echinoblog's Okeanos Explorer Deep-Sea Round Up!

So this week was one of the biggest Marine Biology Events EVER! It was on TV almost ALL DAY (and for the next several days) and involves some of the Earth's most mysterious and unusual animals!

I am of course talking about the 2nd leg of NOAA Okeanos Explorer Northeast US Canyons Expedition 2013!!!  (disclaimer: I am not an employee of NOAA)
Quick Summary: NOAA has a research vessel which travels the world deploying a robot (Remotely Operated Vehicle or ROV) equipped with many HD cameras and a huge ability to record images from the deep-sea.

The Okeanos Explorer has been to Indonesia and many other locales, such as the Galapagos and the deeps off the Caymans, but is currently operating off the east coast of North America, surveying and studying a series of deep-sea canyons and seamounts as seen here.  Those on the legs I've seen (2nd leg?) are in white arrows...

Original Image for this map here

Here is their telemetry which gives you an idea of where they've gone. Some of their dives are VERY deep, down to nearly 3300 meters!!

The Okeanos Explorer is the mothership for the robot (the ROV) which is tethered to the ship as such.. there is an accessory ROV which aids in navigation and so forth...

All of these operations are monitored from a neat control center back on the mother ship...

The AWESOME thing about the OE program is that the HD video from the ROV via the ship can be BROADCAST LIVE OVER THE INTERNET!! 

And so for the last week we have been listening to the awesome narration of two experienced deep-sea scientists: Dr. Martha Nizinski, a deep-sea crustacean specialist at the National Systematics lab in Washington DC and Dr. Amanda Demopoulos, a research ecolgoist/ geologist for the United States Geological Survey

Those who have tuned into the LIVE REALTIME video broadcast have been able to watch "over the shoulder of scientists" as NEW deep-sea habitats are explored!!

What's even more fantastic? Many deep-sea biologists, some world experts in the field, are actually listening in via phone, or via internet forums. I'm one of the world's experts on starfish and I'm monitoring via Twitter (@echinoblog) and via conference call.

Each day of the expedition can go anywhere from 5 to 7 hours. So there's a LOT of footage. So here.. I present some of the highlights of new discoveries and neat, weird deep-sea animals from the last few days of video footage.

There's still more to come and undoubtedly, I've undoubtedly missed some but this gives you a nice overview of new discoveries and awesome stuff from the 1000+ meter deeps off the east coast of North America!

My thanks to Dr. ChrisKellogg (@drchriskellogg) whose "Screen Grab Fu" was FAR superior to mine!

A NEW cold seep community in Nygren Canyon!

A cold seep is a place where toxic materials, such as sulfides, hydrocarbons or methane leech out the bottom and into the water (see here for more info). Animals and other organisms take on special adaptations, such as the ability to absorb and process these toxic materials, so that they can live there in a similar fashion to the way special worms and clams live in hydrothermal vents habitats.

These animals are heavily studied and are important to ecologists as well as physiologists and even scientists researching astrobiology (those that explore how life on other planets originated in extreme habitats)

Cold Seep habitats are unusual and when found, they are often monitored by the scientific community for study because of their potential importance.

This Stalked Crinoid with weird projectons
Stalked crinoids are an older form of crinoids and resemble animals seen in the fossil record (here for some examples)

and certainly the OE expedition saw its share..

What was weird about this one?  look closely...

The stalk is COVERED by tiny little protrusions!!

 

Parasites? Commensals Part of the animal?  A new species?  MANY questions! 

Sea Spiders aka Pycnogonids crawl on deep-sea corals and other cnidarins
Here's one on a sea pen

Another crawling on some deep-sea coral

Weird & Rarely Seen Deep-sea starfish species!
This starfish, called Pythonaster, is known from fewer than 6 specimens in the entire world. This is the 2nd time this animal has been observed alive and the FIRST time it has been observed alive in the Atlantic. 

Here is a plate of this animal from the HMS Challenger Expedition, which described it in 1889!! 

This starfish, Neomorphaster, is better known to scientists, but seeing it alive like this? That's not something that happens often.

This looks to me like the starfish Hymenaster, a member of the Pterasteridae, aka the "Slime Stars" which you can go here to read more about!  See that little center hole on top? That's called the osculum. and that's where the slime comes out! It opens and closes to allow water in and out.

Starfish Eat a LOT of stuff

I've written about deep-sea coral eating starfish before (go here). I've described more than a few species of deep-sea predators. Here's Evoplosoma hanging on and probably feeding on whatever that grey stuff is (probably some octocoral)

Here's an excellent video on these animals, made by the Monterey Bay Aquarium Research Institute

Here is the starfish Solaster which I've written about as a predator on other sea stars (go here)

Is this why so many Neomorphaster are missing two arms???? 

Brittle Stars Live on EVERYTHING
They live on other echinoderms-such as this stalked crinoid

This deep-sea octocoral...

Other animals we saw a lot of....
Barnacles! Deep-sea barnacles are thought to be old relative to their shallow relatives..

Glass Sponges!  aka the Hexactinellida.  These are literally animals made of glass fibers. Their bodies take on really remarkable shapes. There were a lot of these. Especially on Mytilus Seamount. 

This one floats on a long stalk!

whew! Anyway this doesn't scratch the surface of ALL the weird and wonderful things that were seen during the expedition. 

Go HERE to see the Expedition log 

Daily Expedition Updates are HERE.

What more amazing creatures and ecologies will they discover??