Tideline barnacles

Virtually all rocky seashores in Malta sport millions of these unassuming, pyramidal entities that close or open to feed or reproduce depending on the availability of seawater from tide or waves. They are barnacles mostly belonging to the species Chthamalus stellatus Poli, 1791, though other species of Chthamalus are also present on Maltese shores.

As seen in the photograph above (lower right hand corner and upper centre), dead individuals leave behind calcareous volcano-shaped cavities which may be used as a refuge by other intertidal organisms, such as the amphibious and very interesting snail Melarhaphe neritoides (L., 1758) or even other crustaceans such as amphipods. The photograph was taken at Dwejra, Gozo, during receding tide. On the other hand, the photograph below shows completely dry specimens from Buġibba, waiting for the presence of water to resume any activity.

Scorpion, interrupted

I (unintentionally) interrupted this scorpion at Għajn Tuffieħa while it was feasting upon the remains of a fellow arthropod - a hapless woodlouse, which can be seen still attached to the scorpion's jaws in the lower picture. A few seconds after being discovered, the scorpion released the morsel and assumed a compact, defensive stance, remaining utterly immobile until yours truly decided to leave it in peace and restore its stony hideout to its original place.

Only this species of scorpion exists in Malta. It is the small Euscorpius sicanus (Koch, 1837), also found on other Mediterranean islands.

Brocktorff's Maltese fossils

Sir William Reid, Governor of Malta from 1851 to 1858, was a military official and amateur scientist whose interests eventually led him towards a study of meteorology and hurricanes. In a bid to encourage interest in the geology of the Maltese Islands, he published a book containing a few lithographs of fossils commissioned from an artist known only as 'Brocktorff' (Zammit Maempel, 2007).

This book remains very rare in libraries. In addition the well-known echinoids, Brocktorff illustrates remains of crustaceans (a crab), cartilaginous fish (the famous glossopetrae), and bony fish. The following are a some of the illustrated specimens, a few of which are in the National Museum of Natural History, Mdina.

'Schizaster Parkinsoni, Defrance' [*]

'Schizaster Desori, Wright' [**]

'Found at Casal -Luca-Krendi in the Year 1854' [***]

'Found near Casal Luca in the Year 1855'

'Shark's Tooth, with Stony Zoantharia - found near St. Thomas Tower, Malta' [****]

[*] Schizaster parkinsoni (Defrance, 1835)
[**] Schizaster desori Wright, 1855
[***] in contemporary Maltese: Casal Luca = Ħal-Luqa; Krendi = Qrendi
[****] St. Thomas' Tower, Marsaskala

References:

Reid, W., 1857. Maltese fossils lithographed for distribution with the view to encourage further investigation into the geology of the island. Malta: Valletta.
Zammit Maempel, G., 2007. Illustrators and their illustrations of Maltese fossils and Geology. Malta: Publishers' Enterprises Group Ltd.

Dissertation - A student’s guide to the geology of the Maltese Islands

The citation and abstract to my B. Ed. (Hons) dissertation have been added to the links on the right-hand side of this blog. The page can also be accessed through here.

A tenacious fern

Deep inside caves, plant life is either extremely scarce or otherwise totally absent, which is due to the fact that plants need sunlight in order to manufacture food and therefore survive. However, the occasional thin ray of light may sometimes manage its way through, and this is an opportunity upon which mosses and ferns capitalize without fail.

The picture above shows the common maidenhair fern (Adiantum capillusveneris L.) taking advantage of such an instance at Għar Ħassan. The scant sunlight and nutrient-poor limestone soil are enough for the small but hardy plant.

Adiantum is a feature of many 'traditional' Maltese gardens due to its preference for shaded areas. The vernacular name in Maltese is Tursin il-Bir (lit. water-well parsley). Of course, true parsley is a flowering plant, and has nothing to do with the species in question.

Sharks in Malta Part III - Close encounters of the third kind

Today I was surprised that virtually all of the Google searches leading to this blog consisted of the same three keywords: 'shark in Malta'. I attributed this sudden interest to some sensational news item about which I hadn't heard anything so far - and sure enough, one glance at the Times of Malta web portal explained everything.

Without further ado, here's the link to the relevant news item and the accompanying video. Non-Maltese speakers will be disappointed, though!

The Maltese flint

The silicate mineral quartz is, in addition to calcite, one of the commonest minerals on the earth’s crust. An amorphous (non-crystalline) form of this mineral, called variously chert (highly impure) or silex or flint (relatively pure), is found in certain strata of the Maltese rocks.

In a pure state, silicon dioxide is of a transparent colour. This can be seen in crystalline specimens of quartz found in volcanic rocks which are termed ‘rock crystals’. In Malta, nodules or blocks of this mineral contain many impurities mainly consisting of calcium carbonate and other salts; this depends on the parent rock in which they form and results in different colours and varying degrees of translucence.

In the Upper Coralline Limestone Formation, nodules of chert are highly calcareous, opaque and microcrystalline in nature. The impurities in these nodules impart a layered dark brown or charcoal colour. Such nodules are common at the Upper Coralline Limestone of Xemxija and Mistra.

Middle Globigerina Limestone outcrops in Baħrija and Mtaħleb contain usually large blocks of light greyish or khaki chert that intergrades with the limestone and fractures very easily (picture above). Very thin sections of this material allow light to pass through. The parts remaining embedded in the bedrock protrude out and are visible as slightly darker patches against the white limestone.

Middle and Lower Globigerina outcrops in north-central Malta (Mrieħel to Msida) also contain chert, albeit in a the very different form of small to medium-sized nodules. These are somewhat darker in colour, and correspondingly, the silicate material found here is of a light brown to reddish colour.

Odds and ends

Not much time on the laptop on my part has meant a lack of recent blog updates, and for this I do apologize profusely. In the meantime, I have been working on a couple of research papers, two of which which have been submitted and accepted, and some others which are still a long way from being final.

Meanwhile the summery world outside is buzzing with activity, as can be exemplified by the beautiful Xylocopa violacea (L., 1758) below.

This bee is also known as the carpenter bee due to the fact that its eggs are laid inside purposely-bored wood or stems. During my observations I have noticed that the Arundo donax reed is a favoured home for this species.

While the invertebrate world is teeming with insects, however, molluscan representatives are few and far in between, owing to the terrible heat of the Mediterranean summer. The non-marine gastropods that never need worry about this are, of course, those who call freshwater their home, like this Physella acuta (Draparnaud, 1805) from Chadwick Lakes:

Many natural freshwater bodies boast sizable populations of this snail. Other species are much rarer, such as these minute (3mm) Mercuria cf. similis (Draparnaud, 1805) from a Gozitan population: