TAKING A CLOSER LOOK: ROCK POOLS ON ABACO


Rock Pool, Abaco 2

TAKING A CLOSER LOOK: ROCK POOLS ON ABACO

Here’s a promising-looking rocky outcrop a short distance south of Crossing Rocks. The action of the sea over centuries has eroded and pitted it – ideal for the formation of pools in which marine life can thrive.Rock Pool, Abaco 1

Time to clamber up to see if the theory holds good… the prospects are encouraging. There are certainly plenty of sea urchins here.Rock Pool, Abaco 4

Let’s zoom in on the nearest pool. There are clearly 2 different-coloured sea urchins here, but I’m not sure if that’s an age thing or a species thing. Rock Pool, Abaco 6

Apart from the sea urchins, there are some shells and other things that need a closer look…Rock Pool, Abaco 5

At the bottom of these photos, you can see that a zebra-marked nerite is quite happy to share a hole with an urchin. There are two brownish accretions on or in the rock. My tentative suggestion is that these are the shells of some sort of worm, perhaps petaloconchus.

UPDATE Rick Guest helpfully comments “Yes, it’s quite the invertebrate hotel mostly due to the urchin’s talent for scouring out protective “rooms”. Of interest is the Magpie shell (Livona pica) in frames 4 and 5. The rather ubiquitous Livona’s very thick shell, (Up to 5″ diameter) and ability to withstand most attempts at removal by predators, including Homo sapiens, assures their continued presence on littoral shore lines. They are edible, but not particular tasty to my palet. All these “Condo” residents “party” at night and will even leave the rock in search of food and perhaps romance, so a flash pic of the condo at night would be an interesting contrast to a daylight shot”.ROCK POOLS, ABACO 11

In a snug little cave (top right) just above the water-level of the pool is a primitive-looking chiton, a species that has been around for millions of years. Below, there’s a clearer image of one from a different pool. These creatures always remind me of school projects on prehistoric trilobites.Rock Pool, Abaco 7Rock Pool, Abaco 10

The rough rocky surfaces close to the pool are covered in shells. The stripey nerites are small, the grey shells really are miniature.  They are mostly littorines/ periwinkles and perhaps ceriths, I think.Rock Pool, Abaco 9Rock Pool, Abaco 12

Close-up views of nerites showing their distinctive markings and spiralsRock Pool, Abaco 13Rock Pool, Abaco 14

HERMIT CRABS: SHELL-DWELLERS & CONTESTANTS FOR WACKY RACES


HERMIT CRABS: SHELL-DWELLERS & CONTESTANTS FOR WACKY RACES

Hermit Crabs are all around – occasionally (sadly and unavoidably) underfoot. They borrow an empty shell, and as they grow they trade up to a bigger one, leaving their previous home for a smaller crab to move into. It’s a benign chain of recycling that the original gastropod occupant would no doubt approve of… The crabs are able to adapt their flexible bodies to their chosen shell. In the 1st 2 images the crab has chosen a somewhat weathered shell, into which he fits snugly

This small crab has gone for something more modern – possibly quite an awkward shape to lug about…

These crabs have found the Delphi Club bird feeders and taken up residence close by. They forage in the grass, many wearing West Indian top shells. One seems to want to climb the tree to get at the feeder…

They are sensitive to sound: approaching footfalls send them scurrying for shelter into the undergrowth or to holes in the limestone rock. They don’t all manage to fit into a hole so the ‘outsiders’ try to look inconspicuous by withdrawing into their shells, though from a predator’s point of view there are usually a couple of telltale legs sticking out…

Quick, everyone – hide! A human just trod on Derek…An entertaining after-dinner game (and I blame Caroline Stahala for starting this one) is hermit crab racing. Please note that no crabs are harmed in the course of these sporting proceedings, though some crabs may feel a little humiliated. The races can be played for money, of course, but the complete unpredictability and lack of any information about a crab’s previous racing form make that unwise. Far better to have a few drinks first. Then some more afterwards. 

HERMIT CRAB RACING: THE OFFICIAL RULES

  • Dinner is to be completed and drink taken by all participants before racing can commence
  • Each contestant chooses a crab from the group under the bird feeders
  • All chosen crabs are placed in a dish

  • Caroline (or whomsoever shall be designated) paints the shells with each contestant’s name

  • The crabs are lined up by hand on the verandah as straight as they will permit (so, not very)
  • The starter will say “Ready, Steady, GO”, and the crabs are released over a 3 meter course
  • The winner shall be the first crab over the finishing line. In the event of a dead-heat, the crab requiring the least foot-impetus and direction correction is declared winner
  • The crabs shall be returned to the collection site (those that can still be found) and all humans shall return to the Clubhouse for celebrations…

DELPHI HCR RACE REPORT 2012

This crab (the largest) was chosen by Sandy Walker, and regrettably was the only one that started by going backwards. It was never in serious contention

Caroline becomes very overexcited by her crab’s progress

Others resort to unorthodox methods like ‘foot-persuasion’ to keep their crab on course. RH didn’t realise this was allowed at all, and watched his crab dive pathetically off the edge of the verandah into the flowerbed – an irrecoverable drop of 6 inches

Most of the crabs went forwards as intended, though with a certain amount of lateral movement. 2 or 3 seemed to have got the general idea of the race and proceeded more or less according to plan

The impressive winner, by nearly half a minute, was the crab named ‘Emma’. A well-deserved victory, especially as the owner / trainer’s foot-directing was minimal (bare feet!)…

The one thing I would like to know about these little creatures is how they – and their shells – are to be found in large numbers 50 foot above sea-level at the top of a cliff…

BEACHCOMBING WITH KASIA: EXPLORING A ROCKY SHORE


Kasia’s back! She recently explored a rather unpromising-looking stretch of Abaco coastline, and it proved to be anything but… Kasia writes: The story goes: one day I took myself for a walk and a bit of beachcombing. I usually don’t bring my camera with me but luckily this time I did. This particular beach looks very barren but on close inspection and a patient eye there are some lovely treasures to be found. Here are some of the treasures I captured!

A tangle of 3 bleached trees, with their roots apparently intertwined

CHITONS

Great close-ups… are those eggs behind this first one? There’s a similar image in the Macmillan ‘Marine Life of the Caribbean’ but unfortunately neither the caption nor the text refers to them. ADDENDUM: Colin Redfern writes: The “eggs” behind the chiton are fecal pellets

NERITES (Nerita)

 

WEST INDIAN TOP-SHELLS (Cittarium Pica) 

In this image, several very small chitons can also be seen on the rock

It looks as if someone… or something… has been having a Nerite feast on the shore. A bird maybe?  I had taken the shells above and below to be another variety of Nerite, but as so often scientist and shell expert Colin Redfern has kindly corrected the error. He writes: “Very nice photos. The “nerite feast” is actually a pile of broken West Indian Top-shells (Cittarium pica). The photo immediately above shows a live group of the same species. This is what Bahamians call a whelk (or wilk), and in the lower photo they have been harvested, probably for a stew.

 ROCK POOL MISCELLANY

I am trying to ID a much as I can in this pool. All suggestions welcome via ‘Leave a Comment’. So far, the corals are Brain Coral and Pink Coral (I think) but I am going see what else can be given a name…

These are my favourite! :) Kasia

COMET SEA STAR (possibly juvenile, with 3 such short stubs?)

A SPONGE (?) OF SOME SORT (any help with ID appreciated…)

                RED ROCK URCHINS