Wednesday, July 1, 2015

Five Things you Probably Didn't Know about Polychaetes! #InternationalPolychaeteDay

Polychaete worm
This week I celebrate International Polychaete Day which falls on July 1, the birthday of noted polychaete expert Kristian Fauchald, recently of the Smithsonian's NMNH, who passed away in April of this year (2015).
















What are polychaete worms? 
Polychaetes are segmented worms, which are distinguished by their leg like structures called parapodia, which each bear distinct bristles (hair-like structures) known as chaetae which are composed of chitin (the material found in arthropod skeletons).
Alitta virens puziko 2
In the traditional sense, polychaetes are usually classified with earthworms and leeches.  But more recent phylogenetic studies have shown that the "Polychaeta" which used to be a group within the phylum Annelida.  Molecular studies however, have  shown that it is actually a big messy group that likely includes groups of worms which, at one time might actually have been classified as separate phyla !
This includes spoon worms (echiurans)
Eastern Pacific echiurans or spoon worms
and peanut worms (sipunculans)
Phasocolosoma agassizii, Agassizi's Peanut Worm
How many are there and where do they live? 
Its thought that there are likely over 13,000 species of polychaetes which live in every ocean and at every depth (intertidal to >7000 m abyssal depths) and indeed a small proportion of them (about 168 species) even live in freshwater. The diversity of polychaetes is stunning. Those 13,000 species reside within 80 families!!

As I've shown in photo essays here (by Arthur Anker), they can be STUNNINGLY beautiful!

and some, such as these forms from Antarctica can be quite huge.

Feeding ranges from deposit feeding on sediment, filter feeding to of course, raptorial predation which has been made famous by the Indo-Pacific Bobbit Worm! (Eunice sp. )
Rise of the bobbitworm! (Eunice aphroditois)
So, here's five subjective things about polychaetes for IPD!!!

1.  Eat the Palolo Worm! Out in Guam and the Solomon Islands, there are several island cultures who are privileged to be around swimming polychaetes during their reproductive periods, where they undergo a stage/morphological transformation known as epitoky.
The worms swim up into the water column en masse as seen here..
                            
These worms are then promptly eaten by the locals. There are many accounts of this, such as here on National Geographic Palolo worm is considered quite the delicacy and is apparently very reminiscent of caviar and is served here on toast. A traditional presentation.
From MrLavalava's blog!
2. Polychaetes that glow in the dark! 
                            
What would any group of invertebrates be without at least a FEW members that glow in the dark??? (i.e., emit bioluminescence?)

I actually found two: this one is the "Bahamas Glow Worm" aka Odontosyllis enopla. This species looks like a more conventional polychaete

And then you also have the pelagic (aka swimming) polychaete, Tomopteris! which is a bit more unusual given its habitat (the water column)
Image from Wikipedia! 
3. They have a fossil record dating back to the Cambrian
All of the major invertebrate groups can usually be traced back to the very earliest moments in Earth's history when the first evidence of life appears. Polychaetes are no exception.

This pic shows what is thought to be a Cambrian polychaete from the famous Burgess Shale in Canada. It is  appropriately enough called Canadia spinosa
From the Smithsonian's Paleobiology-Cambrian Page! 
The Royal Ontario Museum has a fairly detailed page on this animal here including some nifty paleo art showing what the animal might have looked like alive..
There were apparently a few of these Cambrian polychaetes, including Burgessochaeta,  Phragmochaeta and others..  These were thought to have paddles and interpreted as having the ability to swim. Length: 2-4 cm, so some tiny beasts. 


4. Many polychaete species live in close relationships with other animals
The most photogenic polychaetes might be large predatory ones or possibly even the colorful Christmas tree worms..but there are many polychaetes with a cryptic lifestyle which includes living as a "guest" on other, larger animals.

Sometimes with strong relationships than had been surmised. I wrote about the scale worm Arctonoe vittata a few years ago.  These worms live within the tube foot groove and along the underside of the leather star, Dermasterias imbricata on the Pacific North West coast. 

In experiments, not only did the worms move to the sea stars when separated, but the seastars moved toward the worms! 
Photo by Paul Norwood-from iNaturalist
Scale worms are very dedicated commensals to their hosts.. As I reported from my time in Japan, these stayed with their host, a solasterid until death...





Polychaete worms sometimes have highly specialized relationships. Here are a group of worms known as myzostomes, which are parasites on crinoids. and apparently have been parasitic on crinoids since the Jurassic! (Here
Myzostome 1
5. Many polychaete names are derived from greek mythology: nereids (nymphs) and goddesses!
A comparison of the names of various nereids (sea nymphs or female water spirits) shows that there are in fact a LOT of them shared by a host of polychaete worms..
"Nereid on Ketos" from "Pausilypon" in Naples - beginning 1st century AD - Naples Archaeological Museum - "Augustus and Campania" - Exhibition at Archaeological Museum of Naples, until May 4, 2015
Everything from the genus for the "Bobbit Worm" Eunice sp.
Jack in the box Bobbit Worm
to Nereis which is itself, the Greek word for the water god Nereus
The Worm
Amphitrite, Goddess of the Seas...
Amphitrite
and her terebellid namesake..
DSC_8341
While I'm not privy to the original etymology of these names, its not unusual for the original scientists to name organisms which they perceived as beautiful with namesakes which befitted them...

Happy International Polychaete Day! 

Wednesday, June 24, 2015

Better know The Asterinidae: Familiar & Unfamiliar!

Asteroidia | Asterinidae | Patiriella calcar [Variegated Sea Star] - Flat Rock, Ballina, NSW
A lot of times on the blog, I talk about weird and often unfamiliar groups of echinoderms. But today I thought I would talk a little bit about a family of sea stars, the Asterinidae, which its most likely that most people have seen at some point. They're familiar and as a result, we know quite a lot about some of them..

Members of the Asterinidae include some 150 species in over 25 genera spread out all across the world. Everywhere from the deep-sea to under rocks in the tropical Atlantic and Pacific. Most have five rays, whereas others, such as Meridiastra calcar from Australia can have up to 8 or 9..
Meridiastra calcar #1, Blackmans Bay
The many species go by several familiar common names: Bat star, cushion star, Knitted star..

This is actually a good place to identify the very distinctive patterns in asterinids.. namely, these crescent or "knitted" looking plate patterns on the body surface..
Asterina miniata, Bat Star, Dorsal Surface
               Starphish Asterina (patiria pectinifera) Japan sea, Far East, Primorsky Krai, Russian Federation
In fact, the Japanese word for sea star.. hitode, which means palm, may actually be BASED on an asterinid (Patiria pectinifera).

But for once, there's quite a lot known about them! So here's five subjectively interesting facts about them!
1. They live everywhere
Asterinids occur all over the world with many in shallow water habitats, including under rocks in places as diverse as the North Atlantic. They often live under rocks, or hidden away in cryptic habitats..

There is a HUGE diversity of these tiny little guys. Some are able to reproduce asexually but others just seem to get around.. Being small and easily transported...
serennig - Asterina gibbosa - cushion star
to tropical habitats in Singapore...
Crown sea star (Aquilonastra coronata)
This Callopatiria granifera was a species I observed in Cape Town South Africa!

But honestly, one of the places you are MOST likely to encounter them is here.. in a tropical reef aquarium. These tiny ones are most likely in the genus Meridiastra or Aquilonastra.

Again, this is one of those species which is small and easily transported.. Living rock is a GREAT place for them to turn up..

This aquarium species is asexual and once one gets into your aquarium, you're most likely going to have a bunch of them after too long...

So, you can encounter shallow water asterinids almost all over the world! Australia, South Africa, South America, Antarctica, North America, etc, etc.

But as with most starfish groups, there are often weird deep-sea members... Both of these get to be pretty big sized animals.

I've mentioned these briefly before.. the flat one on the left is called Anseropoda, which is SO flat that it feels like a cloth rag when you pick it up!  We know very little about it.. Sometimes, small ones are so thin that light shines through them! Its name literally means Ansero for "goose" and "poda" for foot.. So, Goosefoot starfish! These can get to be almost 1.5 feet across!

The one on the right, is called Tremaster mirabilis. Katie Gale and her colleagues found that these will feed on coral in the North Atlantic. As a species it occurs widely around the world including the North Atlantic, the South Pacific and near Antarctica.



 2. Funky Feeding
Asterinids practically EMBODY the classic feeding mode of stomach eversion in sea stars! Here's a classic video I've been showing since the blog started!  It shows the stomach extended out onto the glass and feeding on the algae and other good stuff.  Most other asterindis feed in a similar fashion...

Sea star stomach (Bat star)

BUT some are neat ambush predators!! One species in New Zealand.. Stegnaster inflatus pretends to be a cave and can actually AMBUSH tiny swimming crustaceans!!

One of these days, somebody needs to actually make a video of this thing feeding!
This image from SeaFriends in New Zealand













3. Reproduction! Lots of it!  Asterinids are one of the most heavily studied sea stars because of their many reproductive strategies...

Some, such as this "Asterina panceri"(Asterina gibbosa) actually BROOD their young
Asterina pancerii birth
From Byrne 1996, Fig. 4h

and I've reported in the past on this other brooding species, which live inside their mother and whose babies will actually EAT one ANOTHER! 











And of course when all else fails, there's always dividing yourself!  Asexual or fissiparous reproduction is why those tiny aquarium stars are so numerous! 
asterina6361_281111
IMG_3451

3.  Commensal Worms! In the Pacific Northwest species, Patiria miniata, its been know for quite some time that there's actually a species of polychaete worm (Ophiodromus pugettensis) that actually lives on the underside!!
Ophiodromus pugettensis

This is one of the better studied species of asterinids, but there's many other species of Patiria and other species such as Patiriella and Meridiastra which have a similar surface morphology and are conceivably "habitats" for other animals...

4. They are important to the Evolution of Sea Stars!

Here's figure 2 from our paper...
Yeah, I know the image is hard to read, but basically, what I wanted to show was how the Asterinidae seems to show close relations with several other groups of sea stars, including the big multi-armed predators, the Solasteridae
Solaster endeca
and the enigmatic Antarctic Perknaster.. 

Also, the aforementioned Tremaster mirabilis? Sea stars which resemble this species can be found from the Jurassic!  And its position in the tree seems to suggest it might be... interesting..

and of course, there's more I haven't summarized here.. their phylogentic history relative to their various interesting features, etc.. but that's another post!

Friday, June 12, 2015

Lasting Impressions from my Visit to Cape Town, South Africa

So, this is my last 2015 report from Cape Town and its been a GREAT three weeks. I've been working on the collections at the Iziko Museum courtesy of my colleagues at the South African Environmental Observation Network (SAEON).

 Lots of great specimens to study and good interaction with the marine scientific community in the South African region! An extremely productive trip.

Plus, of course, first hand exposure to ecosystems and their faunas! I still marvel at the resemblance between the kelp forests & fauna here and in California!
But here are some lasting impressions that I take away from South Africa that encapsulate the lessons learned over the last few weeks...

1. One of the BEST collections of echinoderms in Africa is at the Iziko Museum! 
This is always kind of a cheat of course. I just spent 3 weeks identifying a massive collection of sea stars, so OF COURSE, I'm a little biased!

But seriously, the collections here contain historical materials from famous echinoderm workers like Hubert Lyman Clark and Ailsa Clark (unrelated). They've maintained a good record of marine biodiversity throughout the region for decades from intertidal to relatively deep-depths.

The Iziko is undergoing many efforts to share its materials with the scientific community including digitzation initiatives and of course a collections database is ongoing!

This is a great place to start your studies on the Indian Ocean or to survey the unusual temperate water habitats of South Africa!


2. Citizen Science is thriving in South Africa!
Perhaps one of the best things I've discovered about the scientific community in the Cape Town and South African is the presence of a very active diving community which LOVES to share and study the marine habitats they observe!

Groups such as iSpotnature.org, SURG (the Southern Underwater Research Group), and even websites such as Eastern Cape SCUBA diving  show a multitude of pictures. This also includes the many pictures off Flickr and other photobanks.. I'm sure there are probably more...


3. There are MANY wonderful ecological and natural history stories in South Africa but they are poorly studied.
Probably one of the great things I learned about studying the fauna is how many cool things are out there and widely known to the local community but were not actually published! 

For example, this amazing sea star, Pteraster capensis has been reported from throughout the area to brood and generate mucus! But was this an actual observation/report? Or simply an extrapolation from the scientific literature on the North Atlantic/North Pacific species?  No scientific reports on this species are available (other than those that report taxonomy).

But I finally spoke to George Branch and Charlie Griffiths at the University of Cape Town who verified that YES indeed. This has been seen!!  So, it will probably make someone a great paper some day!


4. A HUGE diversity of sea stars exists in the region! (and now there is a reference collection!)
As a follow up to the point #3 above, is the simple fact that there is a HUGE diversity of sea stars and other invertebrates on the shores of South Africa. You not only have those animals in the temperate water zones on the west and south coats BUT also the amazing Indian Ocean tropical species on the EAST coast!! Plus the deep-sea!!

I've seen this species for example, identified as "Halityle regularis" in some field guides, but its a different color and is much flatter. Possibly a new record? Or merely a color morph of Halityle? We need to see more than a picture to be sure. I've alluded to possible undiscovered species in past posts...  UPDATE: It IS Halityle regularis-but a different color morph!

BUT thanks to my work at Iziko identifying about 600-700 specimens we know have a bunch of baseline referneces for the fauna of South Africa!  But we will almost always have more pictures than specimens..
5. The staff at the Iziko is AWESOME.
I wanted to thank my hosts at the Museum who helped me with sorting specimens and managing data and other logistics. This includes Candice, Liz, Kanye and of course the curator, Wayne Florence

P.S. The FOOD in Cape Town is AMAZING!

I could NOT have predicted that OSTRICH tastes like very tender beef! Wonderful Grilled or "spicy Mongolian style"!!
Also.. South Africans love cider and meat pies. EVERYWHERE!

THANK YOU CAPE TOWN! I hope to be back!!