Better know The Asterinidae: Familiar & Unfamiliar!

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..

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..

               

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...

to tropical habitats in Singapore...

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...

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

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! 

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!!

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!

A few years ago, I and my colleague Dave Foltz published this DNA tree of one of the most diverse clusters of the Asteroidea- the Valvatacea, which included several members of the Asterinidae. 

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

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!

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!! 

What Have I been doing in South Africa??

Greetings to everyone from Cape Town where I've been for the last two weeks! One more left to go!

Sorry if I've been a bit quiet and off Twitter. What have I been up to? What have I been learning?

1. Identifying Starfish!

image by @MarineBio_SAM

So, it turns out that the South African Iziko Museum's invertebrate zoology collection is probably the largest one of all the collections of its kind in Africa. It includes a huge number of specimens from multiple places throughout the region. So, all major groups have been building up on their shelves.

BUT sometimes, groups need the attention that a specialized scientist, such as myself can offer: in this case the taxonomic skills to identify the many shallow and deep-water species which occur in the very diverse and wonderful waters of South Africa and nearby locales in TWO different habitats: a cold-temperate water setting on the west and south coast AND a tropical water setting on the east coast. Its unusal.

The last starfish/echinoderm expert to visit Cape Town was in the mid 1970s. Specimen collection has been proceeding at a semi-regularr ate for this entire time. And so, there's a LOT of them.

These represent valuable specimens with applications to everything from ecology to natural resource management.

I've identified HUNDREDS of specimens.. some rare. some new. More on this to follow.

2. Learning about South African Starfish!
So, along with what I've been learning from specimens, I've also been in contact with an extensive network of South Africa's marine biologists, citizen scientists, and other ocean-themed folks who are likely to know about echinoderms in the region.

I've been able to experience everything from pictures of living animals to general tips about local species. And yeah.. stuff that will hopefully find its way into a published paper...

3. Observing that temperate water South African marine habitats look astonishingly like those from central California!!

Thanks to some time at the Two Oceans aquarium and talking to colleagues, I have been reminded how stunningly similar (identical) the kelp forests of temperate South Africa can be!

Most folks think of Africa as a tropical locale but I can tell you (especially since I'm here during their winter) that Cape Town gives Monterey, California a run for its money for kelp, urchins, rain and food!

A kelp forest (Macrocystis) off Cape Town

versus a kelp forest (Macrocystis) in Monterey, California

These urchins are Parechinus angulosus (Parechinidae)

these are the  purple  and red California urchins Strongylocentrotus purpuratus and Mesocentrotus franciscanus (Strongylocentrotidae) 

In the case of the sea urchins, they're ENTIRELY different species in different families but they do appear to show some ecological similarities...

4. Giving workshops & presentations on Starfish & more! 
OUTREACH! By now, its probably clear that I am not one to shy away from sharing what I know about echinoderms with everyone.  Part of the plan for my visit to Cape Town was to share what I knew with students and colleagues.

So, far I've given a workshop on the classification and taxonomy of starfish as well as a talk on deep-sea biodiversity at the Two Ocean Aquarium!  One more talk at the University of Cape Town next week!


Have been LOVING talking to local citizen scientists, students and the MANY interested natural history enthusiasts in the area!

5. Encountering familiar names & history far from home....
So, even though I'm on another continent, there are a lot familiar names and a lot of shared history with my other friends and colleagues who have worked in South Africa-especially at the Iziko Museum!

These two specimens for example show collected specimens and work by several of my colleagues. Gary Williams is curator of cnidarians at the California Academy of Sciences. Terry Gosliner, is the curator of mollusks/nudibrancs at the same institution. Angel Valdes is another colleague who works on nudibranchs...

Its interesting how much of what I encounter here is part of this greater shared legacy in Invertebrate Zoology.

Another unexpected finding was this specimen, apparently identified by Smithsonian echinoderm worker and friend, Cynthia Ahearn who passed away many years ago. She often identified specimens for colleagues. This one was from 2002, in her distinctive writing and on a Smithsonian identification tag...












More Next Week!