Sunday, 19 February 2012

Billions of barnacles ~

My first acquaintance with the term 'barnacles' was in the Tintin cartoon books I read as a child: one of Captain Haddock's most common exclamations was "Billions of blistering blue barnacles!"  - what a wonderfully memorable line that was!  Later on I came to know that barnacles form encrustations on the bottoms of boats, where they are a nuisance to boaties and shipping companies alike as they have to be cleaned off regularly.  But I never knew what they actually looked like until very recently.  Once more, my favourite cluster of rocks at the nearby beach proved to be my educator.  

I came across this unusually pretty specimen on a freshly gathered mussel shell, and enquiry and a little reading indicated that it was a barnacle, probably a 'pink' barnacle


I put the host mussel shell into a dish of seawater and watched to see if it would 'do' anything.  If you look carefully at the photograph you can see a little bubble has formed just over the top of it.  Note the two little 'pea' crabs which had been removed from live mussels when they were shelled!

In the image below you can see something beginning to emerge from within the little shell:


I carefully moved the neighbouring shell away to give it more space, and the little soft creature within put its 'head' out:


And looked for all the world as if it was sticking out its tongue and lapping at the seawater!  It went in and out quite slowly and deliberately:


According to what I have read, the bit that pokes out and waves about is actually a 'leg' or hairy feeler, with which the barnacle sweeps plankton and other minute food particles into it's mouth. You can see a short video of how barnacles do this on Wikipedia's barnacle page.

Having done this reading I quickly recognised that the sharp encrustations I climbed over so often at the beach were also barnacles - column barnacles, in fact.  They cover large areas:


Here they are closer up:


Smaller ones, which I'm guessing are juveniles, cover other areas of rock in honeycomb patterns.  They're less sharp but even so...


... this is no place to go barefoot!


Large column barnacles have even encrusted some of the mussels:


Once you have a little information it tends to lead to more, and I was able to identify other types:

These are goose barnacles, or stalked barnacles, I'm not sure which:


And these ones on a paua shell look like 'flat' barnacles to me.  The other possibility is the 'modest' variety:


My purpose here is not to provide definitive answers - I don't have the knowledge for that, but to share my experiences along with some background information and sources.  I hope this adds enjoyment to your own explorations.

You can find my other articles about exploring the beach and its rock pools via the link below: 

Saturday, 18 February 2012

Amazing sea anemones ~ flowery creatures of the rocky shore

I continue to be surprised at what I observe on the rocks. It is certainly true that the more species I become familiar with, the more other ones I notice that I have not previously been aware of. 

I was first alerted to the possibility of sea anemones inhabiting my most familiar set of rocks by the appearance of this tiny one which came home with a bag of freshly harvested mussels.  When I first spotted it it was lodged on a mussel shell.  I couldn't actually see what it was - just a blob of something that must be some sort of creature, and I put the shell it was on into a bowl of seawater as a curiosity.  My reward was almost immediate: once in the seawater it rapidly opened up and made its way off the shell and fastened itself onto the side of the dish. 

Here you can see it in relation to the mussel shell, which shows just how tiny it is:


When it came time to take it back to the beach I had the greatest difficulty prying it off the ceramic surface: it turned back into a dark blob, stuck fast, and its upper surface was unbelievably slippery.  Not wanting to damage it I did my best to be careful, and eventually forced it loose with the edge of a plastic shopping card.  

Once back at the beach I put it in shallow rock pool amongst other growth.  It opened up almost right away and seemed none the worse for its adventures.  I couldn't reunite it with any relations as I'd never seen any, but I realised there must be others!

It seemed almost as if by magic that I spotted a whole cluster of them in a small rock pool just a few days later.  I must have stepped over them dozens of times as I climbed those rocks!


I was astonished and delighted - they had been there all the time and I had never noticed!  How beautiful they are and how delicate.  I gently touched one to see it contract, which it did, just briefly.  Rewi climbed over the rocks after me using his stick to steady himself, and I yelped a warning just as he was about to thrust his stick into that very pool!  Fortunately my warning came in time.

The green anemone might be New Zealand's most common variety, but I had never seen one before.  These are all the more beautiful to me on account of their sensitive camouflage - how delicately and cleverly they blend into their niche!  Now when I step over that pool I always stoop down to admire them.

Later note ~ 19th February 2012:
This morning when I was looking through some earlier photographs I noticed that there were some little green sea anemones in one of them, so I had seen them before, but I hadn't taken them in!  I have often observed this sort of scenario, that once something becomes meaningful to me, I notice it as a matter of course, whereas previously my eyes had passed over just such things without much, if any, awareness.

Further observations added on 16th May 2012:
Since I first wrote this article I've come across lots more anemones and taken plenty of photographs of them from which I have learnt more:

Every time I climb the rocks where I photographed the anemones shown above I stoop down to look at them.  The rock pool in which they live is fairly bare of other little creatures and is far enough above the usual level of sand to have very little sand in it.  I hazarded a guess that they may prefer it that way.  When I checked up on them after a big storm which brought heavy seas I realised why this was likely to be the case: the pounding waves had churned up a great deal of sand and there was a lot in their pool which looked likely to smother them:


Attempting to scoop it away only stirred it up, so I had to leave them alone and see what would happen.  In the weeks that followed we had more heavy seas which washed their faces clean again!


Comparing these two images with the earlier one mades me aware of how much sand they had in them even then!

On another stretch of beach I found this fairy-like community of little ones, none of them larger then a fingernail.  They are underwater, and the water very clear and the pool free of sand.  The unusual blue and white rock is just as you see it in the picture. 


Walking along the beach at the time of an especially low tide I saw this rock face which would normally be underwater: a colony of blue mussels is co-habiting with a colony of anemones.  They are the shiny brownish blobs.  Anemones close when out of water:


It is these blobby forms that you may see on any shellfish you bring home from the beach, so it's worth looking out for them.  As soon as I became aware of what these were I began to place them in my makeshift seawater aquariums which I set up on our dining table whenever Rewi has been gathering mussels:

Here in the bottom of the bowl is a tiny green one all closed up, and no doubt feeling rather battered after I'd edged it off its host mussel shell.  Look at the little speckles of grit attached to it.  I don't know if it has acquired these deliberately as part of a camouflage as some anemones do, or not.


 It soon recovered and opened up:


One day when Rewi gathered mussels from a different group of rocks most of the anemones were orange:


The image below shows how tall their bodies can be.  This one has leant over after I moved the shell it was on and it had insufficient water to stand erect:


When the water got a bit murky and needed changing I noticed that the anemones closed.  The green one doesn't look too impressed either!


One day I was delighted to find these two little red ones.  Here they are getting acclimatised:


And here they have opened up:


Although I enjoy watching anemones in the bowl on the table I take them back to the beach as soon as I can - usually I have to wait a day or so as the pools nearest where they came from are only accessible at low tide.   Before I took these ones back I carried this bowlful out into the sun to see if I could get some nice clear photographs:


All the anemones shown in this article are small with most of them being close to the size of a fingernail.  The exceptions are the four photographed in their rock pool which are quite a lot larger and might be from three to five centimetres in diameter. 

More information can be found via these links:

You can find my other articles about exploring the beach and its rock pools via the link below: 

Chitons on the rocks ~

My first acquaintance with a chiton (pronounced 'kite-on') was unexpected and I had no idea what it was.  Rewi had been gathering mussels, and once back home he found this large lump on one of them which neither of us could identify.  Here it is:
 

It was cool and hard to the touch, so that we weren't even sure if it was a live creature, yet it had an astonishing row of eight shell-like shapes down the centre of its back which seemed to suggest that it must be.  Further enquiry revealed it to be a chiton, probably of the species Eudoxochiton nobilis, otherwise known as the 'Noble' Chiton, no doubt so named on account of its size: it can reach 10cm!  This one was about this length. 
Chitons are characterised by having eight shell-like plates (valves) down their backs which are surrounded by leathery flesh which is described as a girdle.  The whole creature is highly flexible but once it decides to set up camp in one particular spot it is almost impossible to dislodge.  When dislodged it rolls into a ball to protect itself, rather like a slater / woodlouse.

Our household rule is that any live creatures that are inadvertently brought home with the mussels are returned to the sea as soon as possible.  In the interim they are housed in a makeshift aquarium, which is a bowl on the table filled with seawater.  This has also proved to be an ideal place in which to observe and photograph them!   
Note: seawater needs to be replaced at least every day, and preferably more often.

The next time we came across one it was one of the variety most common in New Zealand, a 'snakeskin' chiton, so named because of its banded girdle: once again Rewi had been shelling mussels and I spotted it on the kitchen floor!  Fortunately it hadn't had time to fasten itself to the vinyl and I managed to scoop it up without difficulty and put it in the temporary aquarium.  Here it is in the company of two lively crabs, which had been found inside mussel shells, and a small 'ribbed' mussel.  The little crabs are probably 'pea' crabs.


You can see what a completely different scale it is compared to the one at the top of the page!  Also the detail of colouration is different, and really beautiful.  If you look carefully you can see the rows of hair around the edge of its girdle.


When returned to the beach and placed into this rocky pool it blended in with its surroundings to the extent that it was barely noticeable:


Once I became familiar with chitons I started to see them everywhere:


They blend wonderfully with their own particular places:


I wouldn't mind a bit of wallpaper of this:


Many snakeskin chitons can be found on the surrounding rocks, as can be seen in these images which were taken within close range of each other.

There is certainly an enclave of Noble chitons there as well but their favoured sites seem to be more exposed to the water and waves and are often close to the waterline.  

Chitons can be very mobile, moving about to feed.  Some have an ability to locate back to their exact 'home' spot!  I've looked for this one again, but not seen it there so it may have been out to feed at the time.


This chiton looked like a a young 'Noble' to me: it might have been about 4cm long.  It was highly mobile and seemed keen to explore its temporary home: it glided about busily:





By the time I was ready to return it to the beach it had fastened itself onto the side of the ceramic bowl and I had a hard time prizing it off - it felt like set cement!  Finally it gave up and came away.  Here you can see its underside: it moves about on the central portion which is termed its foot:


I put it into a plastic container with some seaweed and shells, and when I came to take it out it had fastened onto a small shell.  Here it is - from underneath again:


The tide was coming in, and since I didn't want it to get washed away in the waves I carefully pried it off so that it would fasten onto the rock face.  There it would be at leisure to find its way back home:


These seemingly barren rocks are the home of many!  Two Variable Oystercatchers survey the view:


At least twice are day the rocks are inundated by the sea:


I have more to share about these another time...

You can find my other articles about exploring the beach and its rock pools via the link below: 

Tuesday, 14 February 2012

In which I rescue a Yellow Foot paua ~

Rewi and I took a walk along an unfamiliar stretch of beach this afternoon.  It was low tide and many shallow almost muddy pools remained amidst the rocky outcrops and their ropes of seaweed.  I'm always on the lookout for anything unusual and was somewhat startled to see a blobbish shape sporting a bright yellow stripe rotating slowly in the water.  What could it be and why was it in that unlikely pool?  I wondered if it could be a stray paua looking for a rock to fasten onto.  I plucked it out of the water to take a closer look.  It was indeed a paua, easily recognisable once I held it shell-side up. 


'Paua' is the New Zealand term for Abalone.  And I'm fairly sure that the little round attachments on the shell are 'flat barnacles'

Rewi and I immediately had a spirited argument as to its fate: he, the true hunter-gatherer, was all for taking it home and eating it, and I, a naturalist at heart, was determined to rescue and re-home it.  I clinched the argument by declaring that since I had found it it was mine to do what I like with!  Fair enough!  Off we went to find it a new home, but first I had a good look at it:

As soon as I lifted it out of the water it contracted its foot:


The underside of paua is entirely fleshy, and similar to that of a snail.  It both holds on with and moves about on the central portion of flesh, which is termed its foot.  The yellow colour of this one is the source of its common name of Yellow Foot; most paua found in New Zealand waters are Black Foot.  The Yellow Foot is smaller in scale and occurs in far fewer number than the other.

I was amazed at how agile the creature was, so different to the rigidity of its protective shell!  It searched about with its 'foot' looking for something to hold onto:


I rotated it carefully in my hand so that it didn't latch onto me - I didn't want either of us to make any mistakes: 


In the picture below you can see its beautiful pink tentacles and even the veining in the soft white flesh next to the shell:


We looked about for a more suitable spot for it.  Paua like to make their homes fastened onto a rock face hidden from view and near or below the water line.  I found the perfect pool and placed it into it where it could take a look and see if it fancied it.  The sandy bottom of this part of the pool was only a few inches deep in the low tide, and would be way underwater as the tide came back in:


Hmm, evidently it was satisfactory as it delicately reached up and felt around for what could truly be called a foothold!


Got it!  Heigh ho, up we go...


And now it settles in to place:


And after a bit of adjusting itself, it almost completely disappeared:


But we know its there:


And no one else will ever find it!

Rewi and I talked about how it could have come to be drifting about in that first unsuitable pool.  Our guess is that it was prized off its home rock somewhere else by someone harvesting shellfish and then either dropped or thrown back for some reason.  It may have been undersized: Yellow Foot paua must be at least 80mm long when measured across the longest part of the underside.  It seems pretty pointless to have abandoned it in that spot where it couldn't get to any cover, and on a hot sunny day it may have died.  I've read that when returning them to the sea they should be placed foot down onto the reef, which makes sense, if you're handy to a reef!  In this case a handy pool with overhanding rocks was a good and safe choice. 

Today we had another interesting beach find when we inadvertently brought home a rather beautiful chiton, but I'll save that story for another day...

The link below may be useful for shellfish gatherers:

You can find my other articles about exploring the beach and its rock pools via the link below: