ECHINODERMS, DOLLAR DOVES & PETRIFIED BISCUITS


Sand Dollar, Abaco Bahamas (Keith Salvesen / Rolling Harbour)

ECHINODERMS, DOLLAR DOVES & PETRIFIED BISCUITS

Echinoderms (Gr. ‘Hedgehog Skin’) comprise a large variety of sea creatures characterised (mostly) by radial symmetry. In a nutshell a creature with radial (as opposed to bilateral) symmetry can be divided into equal portions from the centre, like a cake. It has no left or right side and no definable front or back.  It is multidirectional from the centre, where the mouth is located. It obviously has a distinct upper side and an underside, but that has no bearing on this form of symmetry. 

Ten dollar Sand Dollar coin, Bahamas

Within the family of radially symmetrical animals, echinoderms (starfish, sand dollars and sea urchins) are unique in having five-point radial symmetry. These are the creatures you are most likely to come across in Abaco. There are two particular aspects of dollars and biscuits that merit a closer look (made more difficult by me stupidly taking photos of white things on a white background).

Sand Dollar Doves, Abaco Bahamas (Keith Salvesen / Rolling Harbour)

DOLLAR DOVES

I’m sure all Bahamians know or are aware of at least one version of the famous ‘Sand Dollar’ poem, in which the various characteristics of the test (the skeleton of the creature) are given religious significance. One verse of the poem may be puzzling: “Now break the centre open And here you will release The five white doves awaiting To spread good will and peace”.

The Sand Dollar Legend

A few years back, Senior Granddaughter was looking at some Abaco sand dollars I’d given her for her growing collection of shells. She picked one up, shook it and it rattled. She said a friend at school had told her that a rattling sand dollar has ‘doves’ inside it, and asked if we could break it open and see. I’ve learnt that it is useless to argue with her – she has the tenacity of a trial lawyer – so we did. This is what we found.

Sand Dollar with a spiky interior like a white cave with stalagmites and stalagtitesSand Dollar Doves, Abaco Bahamas (Keith Salvesen / Rolling Harbour)

Five white doves (in fact, the separated parts of the creature’s feeding apparatus)Sand Dollar Doves, Abaco Bahamas (Keith Salvesen / Rolling Harbour)

Two broken pieces showing where the doves are centrally locatedSand Dollar Doves, Abaco Bahamas (Keith Salvesen / Rolling Harbour)

A regrettably poor photo of a single doveSand Dollar Doves, Abaco Bahamas (Keith Salvesen / Rolling Harbour)

The image below, from Pinterest, shows the ‘mouth’ with its dove-parts intact, in an arrangement called ‘Aristotle’s Lantern‘, a five-sided globular structure that supports the mouth and jaws of an echinoderm.

Sand Dollar : Aristotle's Lantern : Doves (Pinterest)

PETRIFIED BISCUITS

In common parlance ‘petrified’ is an extreme version of ‘terrified’. Literally, it means ‘turned to stone’ (L. petrus, a rock). It is descriptive of a state of fossilisation, where an animal skeleton or dead wood or plant matter turns over aeons into stone. Senior GD (a most inquisitive girl) followed up on the doves research after discovering a box containing random stones and fossils. She found these two items:

Fossilised sea biscuitsPetrified / Fossilised Sea Biscuit (Keith Salvesen)

A closer look at the pair of rocksPetrified / Fossilised Sea Biscuit (Keith Salvesen)

The undersides of the fossils above – looking like stones but with some tell-tale small holesPetrified / Fossilised Sea Biscuit (Keith Salvesen) Petrified / Fossilised Sea Biscuit (Keith Salvesen)

A close-up of the pale biscuitPetrified / Fossilised Sea Biscuit (Keith Salvesen)

Sea biscuits on the beach at Delphi – familiar white skeletons (‘tests’) but not yet fossilsSea Biscuits, Abaco Bahamas (Keith Salvesen / Rolling Harbour)

A ‘modern’ non-Jurassic Abaco sea biscuit in close-upSea Biscuit, Abaco Bahamas (Rhonda Pearce)

FUN FACT

Florida has an unofficial but proposed State Fossil, the ‘Sea Biscuit (Eocene Age)’. I didn’t know it before, but it turns out that more than 40 US States have State Fossils. Whatever next? State Bacteria? State Viruses?

Sea biscuit from Madagascar (OS)

SO HOW OLD MIGHT A PETRIFIED BISCUIT BE?

The fossil biscuits I have looked at, from Florida to Madagascar (see small image above), are said to come from three specific historic epochs – from the oldest, Jurassic (145m – 201m years ago), to Eocene (34m – 56m) and Pleistocene (0.01m – 2.6m). 

HOW DOES THAT HELP ANYBODY? BE MORE PRECISE

By all means. Here is an excellent Geochart that gives an idea of the time span. A Jurassic sea biscuit would be more than 145m years old. This chart also helpfully helps avoid confusion with the Eon Era Period Epoch ordering.

geotimescale

You will find more echinoderm entertainment using this link to my fellow-blogger ‘Dear Kitty’ https://dearkitty1.wordpress.com/2007/01/01/big-hedgehog-small-sand-dollars-diving-schools/

All photos ‘in-house’ except the Delphi biscuits, Clare Latimer; & the single biscuit Rhonda Pearce; Sand Dollar poem on Postcard, Dexter Press; the Geochart was in my ‘useful chart photos’ folder but I can’t now find the source. I did try.

 

SEA BISCUITS: THEY REALLY DO CONTAIN DOVES – AND MORE!


Sea Biscuit Close-up, Abaco (Keith Salvesen)

SEA BISCUITS: THEY REALLY DO CONTAIN DOVES – AND MORE!

Recently I posed the question whether sea biscuits, like sand dollars contain ‘doves’. I had one in my hand, it rattled, I took a photograph through its ‘mouth hole’ and the question was answered. Biscuits do indeed contain doves – see HERE for details and comparisons with dollar doves.

Sea Biscuit 'Doves', Abaco (Keith Salvesen)

However, I spinelessly* failed to break open the biscuit to check out the contents more closely. I theorised that, because of the 5-way symmetry of these creatures, there would be 5 doves (which are in fact segmented mouth parts) in a biscuit exactly as with a dollar, and amiably challenged anyone to disprove it. [* biscuits and dollars are types of sea urchin – see what I did there?]

Dollar dove in close-up – one of 5 segmented mouth parts inside the ‘test’ (skeleton)Sand Dollar 'Doves', Abaco (Keith Salvesen)

Melissa Ann Guinness from Hope Town has a far more robust attitude to these things and, taking up the challenge, she heartlessly smashed open a sea biscuit from her collection to investigate further. I said I’d publish a correction if my theory was wrong. This is it – though in one arguable sense the theory holds good. It just didn’t go far enough…

Sea Biscuit 'Doves', Abaco (Melissa Ann Guinness)

In the above picture you can see (a) 4 quarters of a sea biscuit skeleton (b) 10 demi-doves (rather than 5 whole doves) and (c) a small mummified 5-limbed brittle star that was presumably in the creature’s digestive system when it died.

10 ‘demi-doves’  (or, when assembled, 5 doves that (unlike sand dollars) are in 2 parts
Sea Biscuit 'Doves', Abaco (Melissa Ann Guinness)

Complete doves

Sea Biscuit 'Doves', Abaco (Melissa Ann Guinness) Sea Biscuit 'Doves', Abaco (Melissa Ann Guinness) Sea Biscuit 'Doves', Abaco (Melissa Ann Guinness)

The final reconstruction – 5 doves and a bonus brittle star

Sea Biscuit 'Doves', Abaco (Keith Salvesen)

Photo Credits: Keith Salvesen (1, 2, 3, 10); Melissa Ann Guinness (4, 5, 6, ,7 ,8 ,9)

SEA BISCUITS: DO THEY REALLY CONTAIN DOVES?


Sea Biscuits, Delphi, Abaco (Clare Latimer)

Sea Biscuits on the Beach, Delphi, Abaco Bahamas

SEA BISCUITS: DO THEY REALLY CONTAIN DOVES?

A couple of years ago I wrote a post called ECHINODERMS, DOLLAR DOVES & PETRIFIED BISCUITS. It dealt with the… fact? rumour? old wive’s tale?… that within each sand dollar test (i.e. the white skeleton) are hidden 5 ‘doves’. You can hear them rattling inside if you shake the dollar… 

Sand Dollar Doves (Keith Salvesen) 6

Sand Dollar from Abaco containing 5 miniature white doves…

I investigated the theory with senior granddaughter, and we broke a sand dollar in half. And as you can see, the answer was undoubtedly yes – there were 5 tiny white doves, thus fulfilling the prediction of the famous ‘Sand Dollar’ poem that contains the lines  “Now break the centre open And here you will release The five white doves awaiting To spread good will and peace”.

Five white doves (in fact, the separated parts of the creature’s feeding apparatus)Sand Dollar Doves (Keith Salvesen) 1

A single dove, a picture of dovelinessSand Dollar Doves (Keith Salvesen) 3

I never thought to extend the experiment to sea biscuits, another object prized by beachcombers. All that changed last month when I picked up a sea biscuit and found that it, too, rattled.

A rattling good sea biscuit

So I turned it over to take a closer look at the underside. And there, unmistakably, was the source of the rattle – some kind of internal arrangement inside the feeding  hole (let us not pause overlong to consider the purpose of the other hole). But it wasn’t conclusively a dove.

So I shook it around a bit (sorry, doves) and zoomed in. And there was a small white columbine-type contraption remarkably similar to those found in the dollar dove. And no, I did not smash open the sea biscuit (it wasn’t actually mine). And no, I didn’t doubt any longer that sea biscuits also contain doves.

SO WILL THERE BE 5 DOVES, LIKE WITH THE DOLLARS?

I predict there will also be five. Both dollars and biscuits have ‘five-way symmetry’ (look on the topside of a biscuit or dollar to see how); and so the mouth (from which the ‘doves’ derive) will have a single part for each of the five sectors, all linked. 

If anyone would like to smash up one of their precious beach finds and test the theory, please feel free. Prove me wrong… and I’ll publish a correction! [Photo please…]

All photos Keith Salvesen except Header, Clare Latimer at Delphi

LEAST (BUT NOT LAST) SANDPIPERS ON ABACO


Least Sandpiper, Delphi Beach, Abaco (Charles Skinner)

LEAST (BUT NOT LAST) SANDPIPERS ON ABACO

There are 23 sandpiper species recorded for Abaco. Of those, 4 or 5 are vanishingly rare vagrants recorded once or twice in recent history (i.e. since about 1950).

Discounting those, the ones you are likely to encounter range from the large  (whimbrel, yellowlegs, dowitchers, stilts) to the small. Or, in the case of the least sandpiper, the least big of all. They are bigly little. Least Sandpiper, Delphi Beach, Abaco (Charles Skinner)

The binomial name of the least sandpiper – Calidris minutilla – is an apt clue to their size, the second part being Latin for “very small”. On Abaco, they are fairly common winter visitors, and each season a handful of them make their home on the beach at Delphi, where these photos were taken. Least Sandpiper, Delphi Beach, Abaco (Charles Skinner)

Along with their small sandpiper compadres such as SANDERLING, these busy, bustling birds of the shoreline are the ones known as “peeps” (also as stints). Least Sandpiper, Delphi Beach, Abaco (Charles Skinner)

Least Sandpipers breed in the northern tundra areas of North America. Like many or most shorebirds, newly hatched chicks are able to fend for themselves very quickly. It sounds unlikely I know, but within a couple of weeks or so they have fledged. Least Sandpiper, Delphi Beach, Abaco (Charles Skinner)

The birds forage on mudflats, in the tideline on beaches, and in wrack. They will probe into soft sand, sometimes the full length of their beak. They will even burrow right under weed to get at the concealed goodies. Their diet consists mainly of small crustaceans, insects, and snails.Least Sandpiper, Delphi Beach, Abaco (Keith Salvesen)

Credits: All photos by Charles Skinner (contributor to “The Birds of Abaco”) except the wrack-burrowers above, by Keith Salvesen (also on the Delphi Beach).

Least Sandpiper, Delphi Beach, Abaco (Charles Skinner)

WORLD SHOREBIRDS DAY, PIPING PLOVERS & IRMA


Piping Plover (Danny Sauvageau)

WORLD SHOREBIRDS DAY, PIPING PLOVERS & IRMA

Sept 6 2017. World Shorebirds Day dawns, even as the huge Cat 5 Hurricane Irma makes landfall over the small islands of the eastern Caribbean. Irma’s path has been relentlessly westwards, for sure – but the path has been unnervingly variable. The tracking reports showed Abaco successively as being in line for a direct hit; then taking a sideswipe from the south; then completely clear of the cone prediction; then within the northern edge… and today, a right hook to the east suggests again that Abaco will take a hit from irma (though as a predicted Cat 4 or maybe 3).

Hurricane Irma Tracking Path Sept 6th 2017 Wunderground

Far down the list of concerns in such a situation come shorebirds. Most if not all the islands that Irma will affect have wonderful shorebirds, both permanent and migratory. On Abaco my personal preoccupation is for the tiny Piping Plovers and our citizen scientist annual 6-month WATCH. Generally, the birds manage to find some cover at the back of the beaches to hunker down until the worst is past. But generally the beach populations are rather different after the storm, as birds scatter and take cover. 

Well, except this little guy who decided to take a windy bath on the Long Dock at Cherokee during Hurricane Matthew as it passed over Abaco last October (and props to Keith Kemp for braving the elements to get this shot!)

Birds are resilient and resourceful. Humans too. But nature unleashed with full force is a terrifying prospect. From a safe distance of 4250 miles from Marsh Harbour, thoughts and best wishes from Rolling Harbour will be with all those in the path of Irma over the next few days. 

Piping plovers on the Delphi Beach, at a more peaceful timePiping Plover, Delphi, Abaco (Keith Salvesen)

Photos: Danny Sauvageau, Keith Kemp, Keith Salvesen / Rolling Harbour; Graphic by Wunderground

WHY “ROLLING HARBOUR”? THIS MORNING’S VIEW…


Rolling Harbour, Abaco (Delphi Club Beach)Click to enlarge

SANDERLINGS ON ABACO: GOTTA LOVE ‘EM


sanderling-on-delphi-beach-abaco-keith-salvesen-7

SANDERLINGS ON ABACO: GOTTA LOVE ‘EM

Sanderlings. Wind them up with the concealed key under their left wing, and they will charge up and down the beach for an hour or two, pausing only to rip some small unsuspecting mollusk or crustacean from its sandy bed. These birds are tiny. And smart. They know all about how a retreating tide will expose the goodies. They are even happy to plunge their heads right under water (#2). They’re not really jumpy, if you don’t push your luck or have a dog with you. The best ploy of all is to find a flock near the tideline, choose a place to lie comfortably in dry sand (with a camera, I mean, otherwise you may look look a bit strange), and wait for them to come into range. Usually they are so busy, what with all that rushing around and feeding, that they will ignore you. So the hard part, after you have taken some photos, is catching the little so-and-sos to wind them up again…

sanderling-on-delphi-beach-abaco-keith-salvesen-1sanderling-on-delphi-beach-abaco-keith-salvesen-3sanderling-on-delphi-beach-abaco-keith-salvesen-2

VIDEO 1 In which we notice the scuttling and scooting around of sanderlings on a mission

sanderling-on-delphi-beach-abaco-keith-salvesen-4sanderling-on-delphi-beach-abaco-keith-salvesen-5sanderling-on-delphi-beach-abaco-keith-salvesen-6

VIDEO 2 In which we admire bathtime in a tide-pool and assorted comings & goings…

All photos and movies RH