In this section I introduce some
interesting information about sharks and their abilities, in the form
of questions and answers
Which is the smallest known
The smallest known sharks are two: the dwarf lanternshark, Etmopterus perryi,
maximus 21 cm, and the cylindrical lanternshark, Etmopterus carteri,
maximus 21 cm. Very small sharks are also the pygmy ribbontail catshark, Eridacnis radcliffei,
maximus 24 cm, the african lanternshark, Etmopterus polli,
maximus 24 cm and the green lanternshark, Etmopterus virens,
maximus 26 cm.
(informations from: "Sharks of the world", Compagno-Dando-Fowler,
Princeton University press 2005)
Which is the greatest known shark?
The whale shark (Rhincodon typus) can arrive to a length of 18 m
and with these dimensions he also represents the greatest fish actually
How many sharks are
The sharks actually known, are 453, with 8 orders and 34 families,
following the classification of the books “Sharks of the world” by
Compagno, Dando, Fowler, Princeton University press 2005 and “FAO
Species Catalogue Sharks of the World”, Compagno 2001.
Complete sharks list
Do the sharks have the swimming bladder? How do they succeed in
No, the sharks don't have the swimming bladder (an inside afloat body
that can fill him with gas, present in the bony fishes, whose function
is above all of support to the floating).
The floating of the sharks is facilitated by the cartilagineus structure
and from the great liver that can reach the 25% of the weight of the
Do the sharks lift the head out of the water?
Some sharks, and also the white shark (Carcharodon carcharias),
lift the head out of the water, probably to observe.
Are the sharks animal with cold blood (eteroterm)?
These animals are eteroterm, thay have cold blood (the same temperature
of the water where they swin). Some kinds os sharks, as the white shark,
have a temperature of the body superior in comparison to that of the
water that surrounds them, thanks to the admirable net.
The admirable net is a whole of capillary that have the function of
changing heat, it is connected to muscular bands very developed, next to
the vertebral column. Through the exchanges of heat of the admirable net
the inside musculature and the brain remain to greater temperatures of
those of the water in which these animals swim.
Do fossils of sharks exist?
The sharks have a skeleton made of cartilage and only some parts have
calcified. The cartilage degrades very easily and quickly in comparison
to a bony skeleton. For this motive only teeth and portions of vertebrae
succeed in becoming fossilized and to be studied by the man.
Can the sharks swim to the back?
No, the sharks don't succeed in swimming back (contrarily of the bony
fishes) in how much their pectoral fins are not so mobile to allow them
Does the shark close the eyes during the attack?
Yes, during an attack, for protection, some sharks can rotate back the
eyes to the back (white shark Carcharodon carcharias and mako
shark Isurus oxyrinchus), while others have an eyelid (the
nictitant membrane) that is closed above the eye.
For some instant the shark is therefore deprived of sight and he mainly
uses the ampullae of Lorenzinii to individualize the prey.
Are there predators of the sharks?
The sharks can be plundered by greater sharks and by the orcas. (Orcinus
orca: sea mammal that can overcome the 8 meters of length and the
8000 kg of weight)
Are there sharks that swim in sweet (not sea) water?
Yes, the leuca shark or zambesi (Carcharhinus leucas) swims both
in salty waters and in sweet waters, and in fact he succeeds in also
going up again rivers for hundreds of km (es: river Zambesi).
Are there sharks that eat plankton?
Thin to they are now known three kinds of sharks that are nourished of
plankton filtering the water that enters from their mouth. They are the
whale shark (Rhincodon typus, up to 18 m.) the basking shark (Cetorhinus
maximus, up to 13 m.) and the megamouth shark (Megachasma
pelagios, up to 5 m.).
Do all the actual sharks have the mouth in ventral position?
No, contrarily of the majority of the sharks, the orders
Orectolobiformes and Squatiniformes are composed from sharks
that possess the mouth in terminal position. To the
Orectolobiformeses belong, for example: Stegostoma fasciatum,
Ginglymostoma cirratum, Nebrius ferrugineus, Rhincodon
typus. this last, with a length that can reach 18 m, is currently
the actually known greatest fish.
To the order Squatiniformes belongs, for example, the angel shark
(Squatina squatina), that is a shark from the flat body, whose
gills opening extend until the ventral surface.
Can the hammer shark reproducein asexual way?
Yes. A female exemplary of Sphyrna tiburo has in fact given
birth, in the Henry Doorly Zoo, in Nebraska, not having had contacts
with a male shark from its capture, three years before. Considering that
the ability to preserve the masculine germinal cells (sperms) in the
female of the Sphyrna tiburo doesn't overcome the 5 months, the
birth of the small shark would confirm the asexual way. The female egg
is developed up to form the small shark without the fertilization with a
Does the shark
attack the man?
Only some sharks kinds that reach great dimensions can represent a
danger for the man, as all the great raiders that live on the earth. The
50% of the sharks don't overcome the meter of length, him 82% don't
overcome the 2 meters, and only 4% reach superior dimensions to the 4
meters. The man doesn't reenter among the usual sharks preys.
How many shark attacks happen every year in the world?
Every year, in all the seas of the globe, there are about 60 unprovocked
attacks to the man, about 0-6 deadly.
How many sharks are killed by the man every year?
The man every year captures and kills around 100 million sharks..
Which are the sharks
present in italian waters?
Read the answer
What about the last sharks
attacks in italian waters?
July 1926, Varazze (Ligurian Sea), deadly attack
to a swimmer to around 200 m from shore. (white shark of around six
1956, Circeo (Tyrrhenian Sea), attack to a scuba diver to around 2.5 km
of distance from the beach. (white shark of around four meters)
1962, Circeo (Tyrrhenian Sea), attack to a scuba diver.
1962, Circeo (Tyrrhenian Sea), deadly attack to a scuba diver with numerous
fishes chased suspended on the belt. (white shark)
Riccione (Adriatic Sea), attack to a scuba diver during activity of
fishing. (white shark of around four meters)
1978, Capo d'Anzio (Tyrrhenian Sea), attack to a scuba diver.
(white shark of around five meters)
Riomaggiore (Ligurian Sea), attempt of attack to a scuba diver.
(white shark of around three meters)
Punta Secca (Sicily), attack to a swimmer to around 300 m from the
shore. (white shark of around three meters)
1989, Baratti Gulf (Tyrrhenian Sea), deadly attack to a scuba diver.
(white shark of around six meters)
Marina di Carrara (Tyrrhenian Sea), attack to a surfer extended on the
table. (shark of around three meters)
Portofino (Ligurian Sea), attack to the kayak of a swimmer to around 20
m from the shore. (white shark of around three meters)
Which are the most dangerous sharks?
The most dangerous sharks for the man are:
1) GREAT WHITE SHARK (Carcharodon
2) TIGER SHARK (Geleocerdo cuvier)
3) ZAMBESI SHARK (Carcharhinus
4) MAKO SHARK (Isurus
5) OCEANIC WHITE TIP SHARK (Carcharhinus
Is it possible to see their photos and biological
Is it possible to see white shark in nature and in captivity?
White shark in captivity: the man has never
succeeded in maintaining and therefore to study better a white shark in
captivity, at least up to the year 2003..
It is important to understand that the study in captivity of an animal,
whose presence in the waters of the world is drastically decreased, can
serve to acquire greater awareness on the necessity of protection that
it requires from the man. Examining its behaviors in captivity in fact
the man try to fill those biological and ecological gaps that concern
this shark and at the same time also the exposure to the public can
contribute to cancel so many common places on the so-called one "men's
In the June 2003 for the first time the Monterey Bay
Aquarium in Monterey, California, has succeeded in maintaining in
captivity a white shark for 10 days.
In September 2004 a female, captured for mistake by professional
fishermen, is given to the aquarium and for 198 days this white shark
perfectly suits her for the life in captivity and she is exposed to the
public with great success.
In March 2005 this white shark, not to excessively prolong her
permanence in captivity and to protect her from excessive stress, is
released in open sea and studied for 30 days, aquiring in this way an
important massive structure of data and biological information.
From August 31 st 2006 the Monterey Bay Aquarium holds in captivity
another sample, which shows to have suited well for the new situation,
normally feeding himself and increasing of weight and length.
On January 16 th 2007, after 137 days inside the aquarium, this shark is
released, and thanks to the application of a satellitar tag
(electronic signaller) that April 16 th 2007 is
detached, all of its movements have been reconstructed in open sea
within these three months. The shark has swum up to the south point in
the Baja California, crossing more than 1000 km and reaching depth
superior to the 300 m.
In the month of August 2007 a white shark is accidentally captured by
the net of fishermen, in California, and he is brought to the Monterey
Bay Aquarium, where the animal grows of weight and length for 162 days
to be released in liberty in February 2008. The last white shark that
the Monterey Bay Aquarium has taken care has been in the summer 2009:
the animal as his predecessors, is regularly fed growing of dimensions
and he have returned in liberty November 4 th 2009.
Currently are two the principal destinations in the
world that can be reached to observe the great white shark in nature:
the region of Gansbaai and particularly the island of Dyer in
South Africa and the area of Dangerous Reef, offshore the
peninsula Eyre in southern Australia.
1) Gansbaai is a small village of fishermen
that is found to about two hours with car by the more note Cape Town
(180 km of distance).
The area is enough calm and what can offer is the beauty of its nature,
and also the not scuba tourist can appreciate with long walks along the
The white sharks can be seen in particular way near the island of Dyer,
primarily sandy and distant few km from Gansbaai.
In these zones there are, in fact, numerous seal colonies, together with
their pups, appetizing preys for this great raider of the seas.
As it regards the immersions, there are different centers that organize
exits in sea with the metallic cage to see the white sharks, also
recommend to the beginners, with the desire however to live strong
2) Dangerous Reef owes first of all the name
not to the presence of the white sharks, but to the dangerousness of the
zone for the navigations, near the Gulf of Spencer. This bluff is found
offshore the peninsula Eyre, in southern Australia, also this zone
populated from numerous seals, sea lions and therefore also white
sharks. In this zone and in the near islets can be observed more than
12000 sea lions, the greatest colony in Australia. Also here the not
scuba tourist can appreciate the beauty of the nature, the tones of the
ocean and the beaches, both rocky and sandy, also participating in the
exits of the organizations that transport the scuba divers in the
various zones of immersion.
Also the emerged earth in fact proposes his beauties, without
forgetting, as already mentioned, the numerous seals and sea lions
present in every islet of the zone.
As it finally regards the immersions, also here
they are realized with the aid of the metallic cages of protection, in
surface for the beginners and on the fund for more experts.
What about sharks reproduction?
In the male sharks the terminal part of the pelvic fins, (equal fins
that have the function to stabilize the rout of the animal) become
longer and it calcifies more and more to form the claspers (two), the
sexual organs through which the shark reproduces himself. The
reproduction is internal and appen with the introduction of a clasper
(the other one is a backup) in the cloaca of the female shark. This is a
very bloody moment, in fact the male repeatedly bites the female on the
fins and on the back to stimulate her/ and to hold her firm.
Around the 30% of the sharks has a oviparous reproduction, that is when
the female deposes outside the eggs; around 50% has a aplacental
viviparous reproduction, that is when the female produces the eggs that
develope inside her body and the small sharks go outside completely formed;
the remained 20% has a placental viviparous reproduction, that is when
the embryo is in contact with her mother through a primitive placenta.
Which are the sharks and rays
present in the Adriatic Sea?
Read the answer
Do the sharks have to continually swim to breathe?
Some kinds of sharks (above all the great raiders) have the necessity to
continually swim to make the water pass through their gills and therefore
to breathe. The bentonic sharks, that swin near the fund and generally
of average-small dimensions, can be firm and to breathe inhaling the
water to make it passin their gills. (read
article about SHARKS SPIRACLE)
How many teeth do the sharks have?
The teeth of the sharks are prepared in file, generally six, in the
superior and inferior jaws, and they progressively stir in before, so that to
replace in continuation the teeth of the most external line, more usury
subjects and breakup. In average in the mouth of a shark there are around
300 teeth and during the life they are replaced from there around 20000
a really impressive number!
Why have the hammer sharks the form of the face
so strange and particular?
With this morphology the hammer sharks probably get a best floating
during the swimming and their organs of sense, through a greater surface,
become even more efficient. (see the article"Hammer
Can the sharks perceive the electric fields?
The sharks, through the Ampullae Lorenzinii (to see "The sharks senses")
can perceive variations of electric field of as soon as 5 miliardesimis
of volt for cm. square.
Witch is the pressure of the bite of a shark?
The pressure of the bite of a shark Carcharinus obscurus of around 2
meters would seem to be of three tons for square centimeter!
What are the dimensions of the greatest white shark captured by man?
The greatest white shark (Carcharodon carcharias) has been captured to
Malta, and it was a female of 7,14 meters length. The white shark is the
greatest present predatory shark in the seas of the globe, in fact the
Whole shark (Rhincodon typus, up to 18 ms.) the Great mouth shark (Megachasma
pelagios, up to 5 ms.) and the Elephant shark (Cetorhinus maximus, up to
13 ms.) eat plankton, and therefore aren't not active raiders.
Which kinds of sharks are present in the Mediterranean sea?
In the Mediterranean sea about fifty different kind of sharks are
present, among which the white shark (Carcharodon carcharias) thebull
shark (Carcharias taurus) the fox shark (Alopias vulpinus) the mako (Isurus
oxyrinchus) the grey shark (Carcharinus plumbeus) the verdesca (Prionace
glauca) the common hammer shark (Sphyrna zygaena) the elephant shark (Cetorhinus
Marco Angelozzi - www.prionace.it