الفهرس 
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Abstract
Limpets are various gastropod snails, with a low conical shell,
adhere tightly to rocks with their strong foot. Most limpets have a
definite place of their own on the same rock, and roam up at night to
mate and scrape algae off rocks with their radula then return to the
same spot. In spite, using limpets as a diet; their shells for jewelry and
recently using Keyhole limpet hemocyanin (KLH) as a promising
tumor vaccine carrier, very limited studies are known about them in
Egypt. So, this study planned to throw light on their taxonomy,
anatomy and sperm forms of dominant species. In addition, ecological
investigations and histological and histopathological investigations of
some organs of the dominant species were carried out.
11 limpet species were recorded during the present study at
different habitats of the Egyptian marine water, one of them was
recorded for the first time in Egypt. These species belonging to 2
subclasses, Prosobranchia and Pulmonata; 2 orders,
Archaeogastropoda and Basommatophora; 3 families, Patellidae,
Fissurellidae and Siphonariidae and 4 genera, Patella, Cel/ana,
Diodora and Siphonaria.
The anatomical investigations of Patella caerulea, Diodora italica
and Siphonaria kurracheensis reveal that the shell of P. caerulea is
conical without apical opening or any canal, D. italica has an opening
at the apex of the shell while, S kurracheensis has a small canal at the
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Summary
right side of the shell. The foot is oval in the three species and attached
to the shell by shell muscle. The cephalic tentacles of S. kurracheens is
is flattened and more reduced than those of P. caerula and D. italica.
The mantle cavity of D. italica is larger than those of P. caerula
and S. kurracheensis which contain two bipectinate gills. P. caerula
has secondary gills around all the body. In S. kurracheensis, the gills
are absent but the mantle roof act as a lung for respiration.
The digestive system consists of the same structure in the three
species with few exceptions, such as, the radula has radular cartilages
in P. caerula and D. italica; the oesophagus has many folds also in P.
caerula and D. italica; the intestine of P. caerula is very long, has
many loops and makes fecal pelets; in D. italica, it is short and lacking
loops while in S. kurracheensis the intestine has S-shaped.
The heart is two chambers in P. caerula and S. kurracheensis while
in D. italica it consists of three chambers. The excretory system
consists of two kidneys in P. caerula and D. italica and one kidney in
S. kurracheensis. The sexes are separate in P. caerula and D. italica,
each individual has one large gonad and the fertilization is external
while, S. kurracheensis is a hermaphrodite and use internal
fertilization. The nervous system is similar in the three species which
consists basically of six pairs of ganglia, connecti yes and
comrrussures.
The sperms of Patella eaerulea and Diodora italica are of primitive
type typical to animals using external fertilization. The sperm consists
of a head region which is composed of acrosome and nucleus, a simple
Summary
mitochondrial midpiece and a flagellum with 9+2 arrangement. The
differences between the sperms of the two species represented by
length(L): breadth(B) of the acrosome and nucleus and the number and
shape of mitochondria.
The sperm of Siphonaria kurracheensis is of modified type typical
to animals using internal fertilization. It consists of five divisions, the
acrosome; nucleus; midpiece which composed of three parts, neck
region, glycogen helix and mitochondrial derivative region; glycogen
piece and the end piece.
The ecological studies revealed that, there are marked differences
between stations in Physico-chemical parameters of water. Also, the
heavy metals content in sea water and in soft tissues of Patella
caerulea showed marked differences between stations in most metals
concentrations. EI-Mex station reported the highest values of Cd and
Pb while EI-Anfushi reported the highest values of Co and Zn and
Abu-Qir recorded the highest value of Fe in sea water surface. Heavy
metals recorded highly significant differences between sea water and
Patella caerulea soft tissues.
18 species were collected from Abu-Qir, EI-Anfushi and EI-Mex.
These species belonging to 13 families and 3 classes. Gastropods
dominated the fauna in term of species abundance whi le bivalves
dominated the fauna in term of number of individuals. Patel Iidae was
the most common family of Gastropoda while Mytilidae was the most
common family of Bivalvia. Mytilis minimus was the most abundant
rocky shores molluscs species which dominated all examined stations.
Abu-Qir recorded the highest number of species and individuals
while EI-Mex station recorded the lowest values. El-Anfushi recorded
the highest values of species diversity and evenness and Abu-Qir
recorded the highest value of species richness while EI-Mex recorded
the lowest value of species diversity, evenness and richness.
EI-Anfushi revealed the highest number of limpet individuals and
species while, EI-Mex has the lowest number. Patella caerulea is a
dominant species of genus Patella and Diodora italica is the dominant
species of genus Diodora.
The digestive gland of Patella caerulea made up of branching
tubules, each tubule has a lumen of secretion and two types of cells,
digestive cells and basophilic cells. Samples exposed to 0.5, 0.7 and I
ppm Cd showed no alterations compared to controls after 24 h. but for
48 h., apical microvacuolisation increase and the basophilic cells
decrease. At the same concentrations, an intense autolysis occur for
72 h. while, at 5th day all the tubules showed a great loss in their
structures. Specimens exposed to 1.5 and 2 ppm Cd revealed the
presence of large vacuoles for 24 and 48 h. and the tubules loss their
structure at 72 h. The effect of Cu revealed a great autolysis in all cells
for 72h. at 0.5 and 0.7 ppm and for 24 and 48 h. at I ppm Cu.
The foot of Patella caerulea is formed of pedal epithelium,
compact fibrous layer and muscular portion. The pedal epithelium
consists of two types of cells and the muscular portion contains blood
cells, vesicles, pigments and nerves. The effect of Cd and Cu
represented by the increase of glands content, increase the mucus
secretion and lossing of muscle fibers directions.