Trochoidea

Section dedicated to Molluscs - a group of soft bodies creatures with hard shells such as snails, clams, oysters etc.

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D. Cilia
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Trochoidea

Post by D. Cilia » Thu Nov 15, 2007 11:08 pm

While impatiently waiting for my copy of 'The Non-Marine Mollusca of the Maltese Islands' to arrive, I would like to ask anyone knowledgeable what species of Trochoidea are present in Dwejra, Gozo. I collected five (empty) shells from there recently and there seems to be a huge variation in colour and patterning, yet shell sculpture and overall shape are virtually the same.

Any thoughts?

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Post by MWP admin » Thu Nov 15, 2007 11:35 pm

I suggest to post some photos which makes it easier ! :study:
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FOUR SITES !!

Post by ROLCAM » Fri Nov 16, 2007 4:16 am

Hi David,

It gives me great pleasure to refer you to four specific sites:-

Qawra/Dwejra - UNESCO World Heritage Centre
In fact, on western Gozo one finds an impressive number of solution subsidence
... examples of marine erosion processes at work are present at Qawra/Dwejra, ...
http://whc.unesco.org/en/tentativelists/980/ - 37k


WHTL-980.doc
The Qawra/Dwejra site combines interesting geology, both on land and under the sea,
... to the island of Gozo), and the presence of rare and endangered species.
http://whc.unesco.org/pg.cfm?cid=326&l= ... action=doc -


Suchozemští, sladkovodní a brakičtí měkkýši ostrovů Malty
73-Cochlicella conoidea (Draparnaud, 1801) (01, Gozo). 74-Trochoidea (Trochoidea)
calcarata ... The malacofauna of Maltese republic consists of 91 species, ...
http://mollusca.sav.sk/pdf/2/2.Kolouch.43-50.pdf -


FORMAT DE PRESENTATION DU RAPPORT NATIONAL
species liable to be harmful. No new data is present ...... Dwejra (Gozo),
Il-Ballut ta’ Marsaxlokk, Ir-Ramla tat-Torri and Wied Għollieqa, all ...
http://www.rac-spa.org/telechargement/N ... IIIfin.pdf -

Have a good look at them, you might find what you are looking for.

Bye for now.
Roland Camilleri B.Ec. FCPA.

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Post by D. Cilia » Thu Nov 22, 2007 1:12 am

MWP admin wrote:I suggest to post some photos which makes it easier ! :study:
MWP, I've no adequate camera yet, sorry! Hopefully the coming of Christmas will remedy this

ROLCAM, thanks for the references! No mention of Trochoidea but I did manage to find some info on another (freshwater) gastropod from the area which I found at the 'Qattara' pool, namely Mercuria similis. :twisted:

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More about gastropods.

Post by ROLCAM » Thu Nov 22, 2007 11:10 am

Hi David,


Univalves or gastropods (Gastropoda) are the largest class of mollusks. They include limpets, slugs, snails, and whelks. Most kinds of univalves have a single, coiled shell. The name univalve comes from Latin words meaning one shell. But some kinds of univalves, including garden slugs and the sea slugs called nudibranchs, have no shells after the larval stage.

The name Gastropoda comes from Greek words meaning belly and foot. Gastropods seem to crawl on their bellies, but actually they use a large, muscular foot. The foot spreads beneath the body, and its muscles move in a rippling motion that makes the animal move forward. Most sea snails and some land snails have a lidlike part called an operculum on the back of the foot. When danger threatens, the snail draws back into its shell and the operculum closes the shell opening.

Certain kinds of univalves have two pairs of tentacles (feelers) on their heads. One pair helps the animals feel their way about. Some species have an eye on each of the other two tentacles. Others have no eyes at all. A univalve also has a ribbon of teeth. This ribbon, called a radula, works like a rough file and tears apart the animal's food. Most univalves that eat plants have thousands of weak teeth. A few kinds eat other mollusks, and have several dozen strong teeth.
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Post by IL-PINE » Thu Nov 22, 2007 7:14 pm

well you mentioned the bible of Maltese mollusca there. it is truly a very important book on our land/freshwater mollusca.

Regarding the genus Trochoidea there isn't much of a problem, because we only have 3 living species on our islands namely,

Trochoidea spratti Pfeiffer (which you probably saw) which is common endemic and widespread and has been divided into millions of species in the past, of which today they are all regarded as variations of this one species. Anatomically they are all the same.

[/i]Trochoidea meda is confined mainly confined to gardens and is probably not native. It is not mentioned for Gozo.

The other endemic
Trochoidea gharlapsi was described in 1987 and is confined to the cliffs of southern Malta and Gozo and is quite rare. Might occur in Dwejra though it was not listed as occurring there.

The problem with land molluscs is that for accurate identification, examination of living reproductive parts are required. Iwa trid taqtahulu barra ..... :(

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Post by D. Cilia » Thu Nov 22, 2007 9:23 pm

IL-PINE wrote:Trochoidea spratti Pfeiffer (which you probably saw) which is common endemic and widespread and has been divided into millions of species in the past, of which today they are all regarded as variations of this one species. Anatomically they are all the same.
Prof. PJ Schembri confirms that, thank you. I was initially confused because of the number of forms and variations cited in older literature but now that's been cleared up.
[/i]Trochoidea meda is confined mainly confined to gardens and is probably not native.


It must also have become naturalized to a certain degree, I remember seeing a small number of specimens at the Buskett garigue.

The other endemic Trochoidea gharlapsi was described in 1987 and is confined to the cliffs of southern Malta and Gozo and is quite rare. Might occur in Dwejra though it was not listed as occurring there.


That has been ruled out as well!

The problem with land molluscs is that for accurate identification, examination of living reproductive parts are required. Iwa trid taqtahulu barra ..... :(


Being hermaphrodites, probably not all hope is lost for them :-D

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Hermaphrodite.

Post by ROLCAM » Fri Nov 23, 2007 5:57 am

Hermaphrodite, is an animal with both male and female organs of reproduction. Some flatworms and segmented worms are normally hermaphrodites, as are some echinoderms and mollusks.

Although some hermaphrodites fertilize their own eggs, most do not. Some show successive hermaphroditism, in which the two sets of organs produce eggs and sperm at different times. In others, the positions of the sex organs keep the animals from fertilizing themselves. For example, the common earthworm has active male and female organs located in different parts of the body. This allows two worms to fertilize each other, but prevents them from fertilizing themselves.

In the higher animals and human beings, hermaphroditism is not normal. The organs and functions of one or both sexes usually develop imperfectly in such rare individuals. Few human cases of hermaphroditism have been reported.
Roland Camilleri B.Ec. FCPA.

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Post by MWP admin » Fri Nov 23, 2007 8:22 am

Very informative thanks for the info all of you. One of you should start a MaltaMollusca.com :P I can help in the coding :wink:
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Post by IL-PINE » Fri Nov 23, 2007 12:07 pm

hehe, we might MWP :)

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Post by D. Cilia » Fri Nov 23, 2007 3:40 pm

I'd actually love to see a section on Maltese geology and related sciences!

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Post by MWP admin » Sat Nov 24, 2007 3:24 pm

If you do the research, literatur and photos, I give you the hosting, domain and my own pre-made code similar to www.maltawildplants.com/WildNature.php

Of course, the parametrs would be different according to Mollusca or geology.

F'idejkom l-ahwa!

www.MaltaMollusca.com
www.MalteseGeology.com
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Post by D. Cilia » Sat Nov 24, 2007 4:41 pm

MWP, I just sent you an email as regards the subject. Thanks!

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