The class of the cartilaginous fishes comprises sharks and rays. Chimera
or Holocephali are also members of this class although there are many experts
argue for putting them in their own class. During evolution rays flattened,
developed their pectoral fins into wing-like structures and their mouth
moved to the lower side. Sharks, on the other hand, developed into very
efficient predators and colonized all marine spheres except the very deep
sea. With very few exceptions all cartilaginous fishes fishes live in salt
water.
Sharks can easily be assigned to the 8 orders of sharks. Only the differentiation
between Lamniformes and Carcharhiniformes could present problems in field
studies as it is done on the presence or absence of a nictitating membrane.
There are more than 470 known species world wide and 55 species are
known to occur in Gulf of Mexico and Caribbean.
The order Squatiniformes- Angel sharks; Like saw sharks, angel sharks
are also often misidentified as rays. The most obvious difference is that
angel sharks possess pectoral fins that are not attached to or connected
with the head. Angel sharks also possess an enlarged caudal lower lobe
but, like dogfishes, do not possess anal fins. This order includes 18 species,
most of them of small size. An exception is the japanese angel shark, Squatina
japonica, that reaches 2m. Angel sharks spend most of the day buried in
sand ranging from very shallow water to 1300m. Typical species: Atlantic
angel shark (Squatina dumeril)
Families:Angelsharks, (Squatinidae), Genera Squatina
-
Species (Squatina
dumeril) Sand devil - Harmless. Western Atlantic
Bizarre-shaped shark. Flattened, ray-like form with free anterior
pectoral lobes lateral to the gills. Eyes on dorsal surface, very big spiracles.
Terminal mouth. Both dorsal fins are on caudal peduncle. Lower lobe of
caudal fin is longer than the upper one.
Coloration: Uniformly light beige, no ocelli (dark dots).
The order Pristiophoriformes -Saw sharks: Saw sharks (9 species) are
a very unusual group that is often confused with sawfishes, which are rays.
The most obvious difference between the two is that saw sharks possess
barbels and the teeth, located on the prolonged snout, are different sizes.
Only five species are known. One species, the sixgill sawshark (Pliotrema
warrani), possesses 6 gill slits and lives on the south-eastern Cape Coast
of South Africa. Not much is known about the general biology of this order.
Typical species: American sawshark (Pristiophorus schroederi)
Families: Sawsharks, (Pristiophoridae)
Genera Pristiophorus
-
Species (Pristiophorus
schroederi) American sawshark- Harmless.
Extremly long rostral saw (more than 30% of total body length),
with barbels. Lateral teeth on the saw, about 13 to 14 on each side. Two
dorsal fins. Origin of first dorsal fin about opposite of free rear tips
of pectoral fins.
Coloration: Light brown.
The order Squaliformes - Dogfish sharks: This order represents the
second largest order and includes 7 families and about 113 species and
their most distinguishing feature is the lack of an anal fin. Most species
also have a spine in front of the first dorsal fin. The majority are deep
water species, and some have luminescent organs. Certain species can reach
large sizes for instance the greenland shark, Somniosus microcephalus,
with 7m. Scientists assume that the most abundant species of all known
sharks may be the spiny dogfish, Squalus acanthias, the main species used
for "fish & chips". Typical species: White spotted dogfish (Squalus
acanthias)
Families: Bramble sharks, (Echinorhinidae)
Genera Echinorhinus
-
Species (Echinorhinus
brucus) Bramble shark - Harmless.Western Atlantic: Massachusetts
to Virginia
Scattered thornlike denticles on distributed on body and fins. Both
dorsal fins far back. The origin of the first one is behind the origin
of the pelvic fins. No anal fin.
Coloration: Grey to black.
Families: Dogfish sharks, (Squalidae)
Genera Centroscymnus -
-
Species (Centroscyllium
fabricii) Black dogfish- Harmless.
Small dogfish with green eyes. Two dorsal fins with grooved spines,
second dorsal fin is larger. Origin of first dorsal fin behind the free
rear ends of the pectoral fins. No anal fin.
Coloration: Blackish-brown without white markings. Luminescent organs
present and irregularily scattered.
Genera Cirrhigaleus - Species Centroscymnus coelolepis
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Species (Centroscymnus
owstoni) Roughskin dogfish Need Information.
Genera Dalatias -
-
Species (Dalatias
licha) Kitefin shark- Harmless.
Short, blunt-snouted shark of moderate size. Thick papillose lips.
Two nearly same-sized dorsal fins, no spines. The origin of the first dorsal
fin is behind the insertion of the pectoral fins. No anal fin.
Coloration: Greyish to black or dark brown. "Lips" have a pale coloration.
Edges of fins are mostly transparent.
Genera Euprotomicrus -
-
Species (Euprotomicrus
bispinatus) Pygmy shark Need Information.
Genera Isistius -
-
Species (Isistius
plutodus) Largetooth cookiecutter sharkNeed Information.
Genera Scymnodon -
-
(Scymnodon
obscurus) Smallmouth velvet dogfish - Harmless.
Small shark, with a moderately long, pointed and flattened snout.
Narrow pectoral fins. Dorsal fins with minute, grooved spines. Origin of
first dorsal fin over or at the end of the free rear ends of the pectoral
fins. Pelvic fins about the size of the second dorsal fin. Spiracles present.
Caudal fin with strong subterminal notch and a short lower lobe.
Coloration: Blackish brown or dark brown, no conspicuous markings.
Genera Squaliolus
-
Species (Squaliolus
laticaudus )Spined pygmy shark) Probably the smallest shark
of all, maximum size about 25cm. - Harmless.
Very small, spindle shaped body. Pointed, long and bulbously shaped
snout. The only known shark with a spine on its first dorsal fin but not
on the second one. First dorsal fin with its origin opposite to the inner
margins or rear tips of pectoral fins. No anal fin.
Coloration: Dark (black) with conspicuously light-margined fins.
Genera Squalus
-
Species (Squalus
acanthias) Piked dogfish- Harmless.
Small shark with two dorsal fins with ungrooved large spines. No
anal fin. First dorsal spine origin is behind the pectoral rear tips. Lateral
keels on caudal peduncle and upper precaudal pit. No subterminal notch
on the caudal fin. No anal fin.
Coloration: Grey-brown upper body with whitish ventral surface. White
spots along entire body.
The order Carcharhiniformes - Ground sharks More than half of all known
shark species are ground sharks. This order represents the most typical
sharks, such as grey reef shark, Carcharhinus amblyrhynchos, and the blue
shark, Prionace glauca. This order consists of 8 families with more than
259 species. Their distinguishing features are a nicitating membrane (a
flap of skin that functions as a third eye lid), 2 dorsal fins, an anal
fin and five gill slits. Most of these sharks are found in tropical and
temperate waters. Ground sharks possess all forms of reproduction such
as oviparity, aplacental viviparity (ovoviviparity) and viviparity. Typical
species: Silky shark (Carcharhinus falciformis)
Families: Catsharks, (Scyliorhinidae):
Genera Apristurus
-
Species (Apristurus
parvipinnis) Smallfin catsharkNeed Information.
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Species (Apristurus
canutus) Hoary catshark - Harmless.
Relative slender body slightly tapering toward head. Moderately
long snout, bell-shaped and broad. (Preoral snout about 9 to 10% of total
body length). Broad nostrils. Relatively large eyes (3 to 4% of total body
length). Labial furrows present, positioned directly under the eyes. First
dorsal fin about half the size of the second one. Origin of first dorsal
fin slightly behind the insertion of the pelvic fins. Origin of second
dorsal fin well in front of anal fin's insertion. Body surface almost silky-smooth
(no fuzzy or feltlike texture).
Coloration: Dark grey with blackish fin margins.
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Species(Apristurus
laurussoni) Iceland cashark - Harmless.
Relatively slender body, with trunk tapering slightly toward the head.
Broad and moderately long, bell-shaped snout (preoral snout about 7 to
8% of total body length).. Adults have small eyes. Short gill slits. Large
nostrils (incurrent and excurrent apertures large and oval). First dorsal
fin about as large as second dorsal fin. Origin of first dorsal fin slightly
anterior to the midbases of pelvic fins. Insertion of second dorsal fin
about opposite insertion of anal fin. Pelvic fins high and broadly rounded.
Short anal fin (slightly more than three times as long as high).
Coloration: Dark brown, no conspicuous markings.
Genera Parmaturus -
-
Species (Parmaturus
campechiensis) Campeche catshark - Harmless.
Slender, soft shark with relatively small dorsal fins. Origin of
first dorsal fin over the origin of the pelvic fins. Second dorsal fin
opposite the anal fin, both of same size. Broad snout, rounded. Gill slits
are concavely shaped.
Coloration: Uniformly colored, grey-brown to grey-black, without conspicuous
pattern. Ventral surface very light.
Genera Schroederichthys - Species Schroederichthys tenuis
-
(Schroederichthys
maculatus) Narrowtail catshark Need Information.
Genera Scyliorhinu
-
Species (Scyliorhinus
retifer) Chain catsharkNeed Information.
Families: Finback catsharks, (Proscylliidae)
Genera Eridacnis -
-
Species (Eridacnis
barbouri) Cuban ribbontail catshark- Harmless.
Very slender, small shark. Nicitating membrane present. Two equal-sized
dorsal fins. The position of the first dorsal fin is closer to the pelvic
fins than to the pectorals. Very slender caudal fin.
Coloration: Light grey, with dark stripes over the caudal fin.
Families: Houndsharks, (Triakidae)
Genera Galeorhinus -
-
Species (Galeorhinus
galeus)Tope shark Endangerment: Threatened, since overfished.
A slender houndshark with a long snout. Large horizontally oval
shaped eyes. Origin of the first dorsal fin is over or slightly behind
the free rear ends of the pectoral fins. Second dorsal fin is much smaller
than first one and is of similar height as the anal fin that is opposite
to it.
Coloration: Bronze to grey-brown upper body, whitish pale ventral surface.
Families: Weasel sharks, (Hemigaleidae)
Families: Requiem sharks, (Carcharhinidae)
Genera Carcharhinus
-
Species(Carcharhinus
signatus) Night shark - Harmless.
Large requiem shark with long and pointed snout. Circular eyes (diameter
1.8 to 2.7% of total body length). Small gill slits (height only about
2.5% of total body length). First dorsal fin is small and triangular with
origin over the free rear tips of pectorals. Second dorsal fin is small
and low (height about 1.7 to 2.1% of total body length) with origin over
or slightly posterior to origin of anal fin. Pectoral fins slightly falcate,
moderately long with narrow rounded apices. Interdorsal ridge present.
Coloration: Grey upper body, white ventral surface. No conspicuous markings.
Sometimes has small black spots scattered over the body and an inconspicuous
white band can be present over the flank.
-
Species (Carcharhinus
brachyurus) Copper shark - Potentially dangerous.
Fairly slender shark. Moderately long snout, narrowly rounded or
pointed. First dorsal fin falcate and large with a pointed apex. The origin
is over or slightly anterior to the pectoral rear tips. Second dorsal fin
is small and low with an origin over or slightly posterior to the anal
fin's origin. Long and falcate pectoral fins. No interdorsal ridge.
Coloration: Bronze or grey,with white ventral surface. Most fins with
inconspicuous darker edges and dusky to black tips. A moderately prominent
white band on the side.
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Species (Carcharhinus
perezi) Caribbean reef shark - Accidents are known and it is
a potentially dangerous species.
A stocky shark. Short, bluntly rounded snout. Origin of first dorsal
fin over the free rear ends of pectoral fins. Second dorsal fin with a
short rear tip and its origin is over or slightly anterior to the anal
fin's origin. Large narrow pectoral fins. Weakly developed interdorsal
ridge.
Coloration: Grey to brownish on the back, bronze colored on the sides,
with white ventral surface. Underside of pectorals, pelvic fins, anal fin
and ventral lobe of caudal fin are dusky colored.
-
Species (Carcharhinus
altimus) Bignose shark - This species does not seem to be a
threat to people because of its deepwater habitat.
Large shark with a rounded or bluntly pointed snout. Prominent nasal
flaps. Nearly straight pectoral fins. The origin of the first dorsal fin
over pectoral fin insertion to about over the mid length of the pectoral
inner margins. Prominent interdorsal ridge.
Coloration: Light grey upper body, sometimes even slightly bronze coloration,
with a white belly and dusky fin tips, except for the pelvic fins. No conspicuous
markings.
-
Species (Carcharhinus
acronotus) Blacknose shark - Harmless to humans, although a
possible threat display known as "hunching", where the back is arched and
the head raised, has been seen in animals in captivity.
A small, slender shark with a moderately long and rounded snout.
Origin of the first dorsal fin over the pectoral fins' free rear tips.
First dorsal fin and pectoral fins are small. No interdorsal ridge.
Coloration: Grey, greenish grey, sometimes yellowish grey or brown above
with a dusky or black spot on the underside of the snout tip. Younger specimen
possess a more prominent black spot. Black or dusky tips present on the
second dorsal fin and dorsal caudal lobe.
- Species (Carcharhinus
amblyrhynchos )Grey reef shark - Accidents are known. Grey reef
sharks are known to "hunch" when feeling threatened. Indian Ocean: Madagascar,
Seychelles, and the Maldives. Western central Pacific: Thailand, Australia,
New Caledonia, Philippines, Indonesia, east to the Hawaiian Islands and
the Tuamoto Archipelago, Tahiti.
Medium-sized to large shark, with a broadly rounded snout. Origin of
the first dorsal fin usually over or just in front of the free rear tips
of the pectoral fins. No interdorsal ridge.
Coloration: Grey upper body and white ventral surface. First dorsal
fin entirely grey or irregularly white-edged. The entire posterior margin
of the caudal fin shows a conspicuous broad black margin. Pectoral fins,
second dorsal fin, anal fin and pelvic fin with blackish or dusky tips.
-
Species (Carcharhinus
brevipinna) Spinner shark - This species is not dangerous to
human beings, although it could be troublesome to divers when spearfishing.
Large and slender shark with a long and pointed snout. Small eyes.
First dorsal fin is small and semifalcate. Origin of first dorsal fin usually
over or slightly posterior to pectoral free rear tip. No interdorsal ridge.
Coloration: Grey-bronze coloration, white belly. Most often with a narrow,
white band on flanks, sometimes not conspicuous. Large juveniles and adults
with black tips on pectoral fins, second dorsal fin, anal and ventral caudal
lobe, and sometimes on pelvic fin, first dorsal and fin and dorsal caudal
lobe, too.
-
Species (Carcharhinus
falciformis) Silky shark - Silkies are generally regarded as
dangerous or potentially dangerous to people, mainly due to the their size
and abundance offshore, although no attacks have been attributed to them.
When approached by divers, individuals have been seen to perform a "hunch"
display, with back arched, head raised and caudal fin lowered, possibly
as a defensive threat display.
Large, slim shark with moderately large eyes. Long rounded snout.
Origin of first dorsal fin behind the free rear tips of the pectoral fins.
Interdorsal ridge present.
Coloration: Dark grey, grey brown or bronze brown upper body, sometimes
nearly blackish, white ventral surface. The tip of the first dorsal fin
is dusky but not black-tipped. Inconspicuous white band on flank.
-
Species (Carcharhinus
galapagensis) Galapagos shark - Potentially dangerous species.
Galapagos sharks perform a "hunch" threat display, with an arched back,
raised head, and lowered caudal and pectoral fins, while swimming in a
conspicuous twisting, rolling motion.
Large shark with a moderately long broadly rounded snout. Origin
of the first dorsal fin over the mid lengths of inner margins of the pectoral
fins. A low interdorsal ridge is present.
Coloration: Brownish-grey upper body, white ventral surface. The tips
of most fins are dusky but not black. An inconspicuous white band on the
flanks can be seen.
-
Species (Carcharhinus
isodon) Finetooth shark - Not dangerous.
Small shark. Moderately long pointed snout. Fairly large eyes and very
long gill slits. Origin of first dorsal fin over or only slightly behind
to the insertions of the pectoral fins. No interdorsal ridge.
Coloration: Dark grey or bluish grey above and white below with an inconspicuous
white band on the flank. No conspicuous markings on fins.
-
Species (Carcharhinus
leucas) Bull shark - Probably the most dangerous species of
tropical waters. Bull sharks are one of the three most dangerous species,
beside the white shark ( Carcharodon carcharias ) and tiger shark ( Galeocerdo
cuvier ) It would not be surprising if the bull shark would turn out to
be the most dangerous shark species, because of its large size, massive
jaws, proportionately very large teeth and abundance in the tropics.
Stocky to very heavy-bodied species. Very short and broadly rounded
snout. Small, circular eyes. First dorsal fin large and broadly triangular
to somewhat falcate. Origin of the first dorsal fin usually over or just
behind the insertions of the pectoral fins. No interdorsal ridge.
Coloration: Pale to dark grey. Fin tips are dusky, but not strikingly
marked. An inconspicuous white band on the flanks.
-
Species (Carcharhinus
limbatus) Blacktip shark - Very few attacks on people have been
attributed to this species, and it is likely that without a food stimulus
or other special circumstances that this species is of little hazard to
people.
Shark with a long and pointed snout. Small eyes. Origin of the first
dorsal fin usually over or slightly behind the insertion of the pectoral
fins.
Coloration: Grey, grey-brown or bluish grey upper body, white ventral
surface. Black tips usually present on pectoral fins, second dorsal fin,
and ventral caudal lobe, and sometimes on pelvic fins. The tip of the anal
fin is usually plain. A conspicuous white band on the flanks.
-
Species (Carcharhinus
longimanus) Oceanic whitetip shark - Dangerous species.
Large, stocky build, with a short blunt snout. Long, broad and paddle-shaped
pectoral fins. High first dorsal fin. Origin of the first dorsal fin just
in front of the pectoral free rear tips. Interdorsal ridge, may be absent
or only weakly developed.
Coloration: Grey-bronze upper body, white ventral surface. White mottling
usually present on fins, particularly on the pectorals, first dorsal fin,
pelvic fins and caudal fin tips. Flank with an inconspicuous white band.
- Species (Carcharhinus
melanopterus)Blacktip reef shark - Not in Gulf of Mexico and
missrepresented This species prefers shallow waters close inshore on coral
reefs, at depths of only a few meters and commonly in the intertidal zone,
often on reef flats in water 30 cm deep or less.
Small typical requiem shark with a short, bluntly rounded snout. Horizontally
oval eyes. Origin of the first dorsal fin is usually over the pectoral
free rear tips. No interdorsal ridge.
Coloration: Usually light brown upper body, white ventral surface. First
dorsal fin and ventral caudal lobe have a conspicuous black apical blotch,
which is brilliantly highlighted proximally with white. A conspicuous white
band on the flanks.
-
Species (Carcharhinus
obscurus) Dusky shark - Potentially dangerous.
Large, with a short, broadly rounded snout. Fairly large eyes. Origin
of first dorsal fin is usually over or slightly in front of the rear tips
of the pectoral fins. Low interdorsal ridge.
Coloration: Blue to grey upper body, white ventral surface. The tips
of most fins are dusky, not black or white. Inconspicuous white band on
the flanks.
-
Species (Carcharhinus
plumbeus) Sandbar shark - Harmless.
Medium-sized requiem shark. Round snout. First dorsal fin prominent,
very high, with a rounded apex. Origin over or slightly anterior to pectoral
insertions (ends). Second dorsal fin moderately high as well (2.1 to 3.5%
of total body length). Origin over or slightly anterior to anal fin origin.
Large pectoral fins, semi-falcate with narrowly rounded or pointed apices.
Interdorsal ridge is present.
Coloration: Grey-brown upper body, white ventral surface. Tips and posterior
edges of fins can be dusky colored but no conspicuous markings.
-
Species(Carcharhinus
porosus) Smalltail shark - Harmless.
Small requiem shark, with a moderately long and pointed snout. Eyes
are large (diameter about 1.6 to 2.5% of total body length). First dorsal
fin is large and falcate, bluntly rounded apex. Origin over the inner margins
of the pectorals (can also be found slightly posterior to pectoral insertion).
Second dorsal fin relatively low (2.2 to 2.8% of the shark's total body
length). Origin over or slightly behind the midbase of the anal fin. Small
pectoral fins, falcate and narrowly rounded or pointed. No interdorsal
ridge present.
Coloration: Grey upper body, light ventral surface. Tips of pectoral,
dorsal, and caudal fins sometimes have inconspicuous dusky or blackish
marks. Sometimes have an inconspicuous white band on flanks.
Genera Galeocerdo -
-
Species (Galeocerdo
cuvier) Tiger shark - Potentially dangerous.
Unmistakable requiem shark with a very short, blunt snout, labial furrows
and big head. Spiraculi present. Slender body behind the pectoral fins.
Origin of first dorsal fin over free ends of pectoral fins. Low keels on
caudal peduncle, slender and long caudal fin.
Coloration: Dark grey with vertical tiger-stripe markings; can fade
or be obsolete in adults.
Genera Negaprion
-
Species(Negaprion
brevirostris) Lemon shark - Potentially dangerous.
A short-nosed, stocky shark with big eyes. Snout is wider than long.
Both dorsal fins are of equal size. Origin of first dorsal fin over free
rear ends of pectoral fins.
Coloration: Yellow-brownish, with white ventral surface.
Genera Prionace
-
Species(Prionace
glauca) Blue shark - Seems to be potentielly dangerous, although
questionable.
Slender, with long pectoral fins. Narrow head, with a parabolic snout
(from dorsoventral view). Big eyes, without posterior notches. No spiracles.
Origin of first dorsal fin behind the free ends of pectoral fins. No interdorsal
ridge. Small keels on caudal peduncle.
Coloration: Intense blue upper body, white ventral surface. No color
pattern.
Genera Rhizoprionodon
-
Species(Rhizoprionodon
terraenovae) Atlantic sharpnose shark - Harmless.
Small shark. Long, parabolic snout, with long upper furrows. Nostrils
are far apart. Big eyes. Origin of first dorsal fin before or slightly
before the free rear ends of the pectoral fins. Origin of second dorsal
fin above midbase of anal fin or just in front of its insertion. No spiracles.
Coloration: Grey to grey-brown with white ventral surface. Adults have
small light (white) dots on body, white margins on pectoral fins and and
dusky dorsal fin tips.
-
Species (Rhizoprionodon
porosus) Caribbean sharpnose shark Since this species is heavily
fished, it must be considered threatened.
Small shark. Long, parabolic snout, with long upper furrows. Nostrils
are far apart. Big eyes. Origin of first dorsal fin before or slightly
before the free rear ends of the pectoral fins. Origin of second dorsal
fin above midbase of anal fin or just in front of its insertion. No spiracles.
Coloration: Grey to grey-brown with white ventral surface. Adults have
small light (white) dots on body, white margins on pectoral fins and and
dusky dorsal fin tips. .
Families: Bonnethead sharks, (Sphyrnidae)
- Genera Sphyrna -
-
Species(Sphyrna
tiburo) Bonnethead - Harmless.
Very small hammerhead. Unique and very narrow, shovel-shaped head without
an indentation on the anterior margin. Origin of first dorsal fin over
the inner margins of the pectoral fins. Rear tip of the first dorsal fin
ends in front of the pelvic fins.
Coloration: Grey-brown, white ventral surface.
-
Species (Sphyrna
zygaena) Smooth hammerhead - Potentially dangerous.
Large hammerhead. Broad and narrow-bladed head with a broadly arched
anterior margin and no median indentation. First dorsal fin is moderately
falcate with a free rear tip that is in front of the pelvic fins' origins.
Origin of the first dorsal fin is over the pectoral fins insertions. Second
dorsal fin is low and shorter than the anal fin. Pelvic fins are not falcate.
Precaudal pit present.
Coloration: Dark olive to grey-brown with white ventral surface. Undersides
of pectoral fin tips are dusky colored.
-
(Sphyrna
media) Scoophead - Harmless.
Small, with moderately broad and anteriorly arched hammer (mallet-
shaped head), weak medial and lateral indentations on its anterior edge
and transverse posterior margins. First dorsal fin falcate with the free
rear tip ends over the pelvic origins. Origin of first dorsal fin over
the inner margins of the pectoral fins. Second dorsal fin moderately high,
not reaching the caudal fin with its free rear end. Precaudal pit present.
Coloration: Grey-brown with white ventral surface.
-
Species(Sphyrna
lewini) Scalloped hammerhead - Potentially dangerous.
Large, with a broad, narrow-bladed head. Anterior margin of "hammer"
is very broadly arched in adults, with a prominent median indentation.
Somewhat falcate first dorsal fin with an origin over or behind the insertion
of the pectoral fins. Free rear end of second dorsal fin nearly reaches
caudal fin. With precaudal pit.
Coloration: Grey-brown (olive), with white ventral surface. Dusky to
black pectoral fin tips. Juveniles can have dusky coloration on the tips
of the pelvic fins, the lower lobe of caudal fin and the free rear end
of the second dorsal fin.
-
Species(Sphyrna
mokarran) Great hammerhead - Potentially dangerous.
Very large hammerhead shark. Anterior head margin nearly straight,
with a median indentation. First dorsal fin very long, erect and falcate
with the rear tip in front of the pelvic fin's origin. Second dorsal fin
is high with a concave posterior margin. Falcate pelvic fins. Great hammerhead
has a much higher first dorsal fin making mis-identification very unlikely
Coloration: Bronze to grey-brown with white ventral surface. Adults
have no markings on fins, while in juveniles the second dorsal fin tip
is dusky colored.
The order Lamniformes - Mackerel sharks consist of 8 families and 17
species. They are a rather diverse group that lack a singular distinguishing
characteristic and a combination of different features is needed such as:
Origin of mouth behind the eyes, conical snout, a pair of 5 gill slits,
2 dorsal fins, no nicitiating membrane. Many of the sharks possess a counter-current
circulatory system. This system enables them to maintain a higher body
temperature and live in colder waters. Mackerel sharks include the biggest
and fastest predators like white sharks (Carcharodon carcharias) or makos
(Isurus oxyrinchus). Most Mackerel sharks can raise their body temperature
by means of a heat exchange system (rete mirabilis). There are only 16
species of mackerel sharks, belonging to 7 different families and 10 genera.
Typical species: Blue pointer (Isurus oxyrinchus)
Families: Sandtiger sharks, (Odontaspididae)
Genera Carcharias
-
Species (Carcharias
taurus) Sandtiger shark - Harmless.
Large shark with a flattened-conical snout. Body is compressed-cylindrical
and moderately stout. First and second dorsal fin are equal sized with
a broad base. Origin of first dorsal fin well behind the free rear ends
of the pectoral fins. Origin of second dorsal fin slightly ahead of anal
fin's origin. Anal fin is approximately the same size as the two dorsal
fins. Upper caudal pit is present. Teeth are very prominent, with large
narrow cusps and lateral cusplets.
Coloration: Light brown upper body, white ventral. Often has darker
reddish or somewhat brownish spots scattered over the body.
Families: Crocodile sharks, (Pseudocarchariidae) Genera Pseudocarcharias
-
-
Species (Pseudocarcharias
kamoharai) Crocodile sharkProbably worldwide in tropical waters.
Western Atlantic: Cuba to northern Brazil. Small and very unique looking
shark. Very big eyes, no nictitating membrane. Long gill slits. Small pectoral
fins, small dorsal fins. Weak keels on peduncle, precaudal pit present.
Asymetrical caudal fin (not lunate-shaped).
Coloration: Greyish-brown with white ventral surface. Sometimes
seen with white dots. All fins have white margins.
Families: Thresher sharks, (Alopiidae)
Genera Alopias
-
Species(Alopias
superciliosus) Bigeye thresher - Harmless. Large shark with
a very long caudal lobe that is nearly as long as the rest of the body.
Huge eyes. Notched or helmeted contour of head. Origin of first dorsal
fin well behind the free ends of the pectoral fins. Pelvic fins large and
nearly as large as first dorsal fin. Falcate and broad-tipped pectoral
fins. Second dorsal fin and anal fin very small. Precaudal pit is present.
Coloration: Violet-grey upper body, whitish ventral surface.
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Species (Alopias
vulpinus) Thresher shark - Harmless. Typical thresher shark
with a very long tail. The upper lobe is about half the entire size of
the shark. Small eyes with orbits that do not expand onto dorsal surface
of head. Forehead is strongly convex in lateral view. Frist dorsal fin
erect and angular. Pectoral fins are falcate and narrow-tipped.
Coloration: Dark, metallic shine, ventral surface white extending
over pectoral fins bases as a very conspicuous patch.
Families: Mackerel sharks, (Lamnidae)
Genera Carcharodon
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Species (Carcharodon
carcharias)Great White Shark - Highly dangerous.
Heavy spindle-shaped body, with a moderately long and pointed snout.
Large gill slits. Origin of first dorsal fin over the free ends of the
pectoral fins. Minute second dorsal fin. Very large pectorals. Crescentic
caudal fin, strong keels on peduncle.
Coloration: Blue-grey to grey-brown coloration on back, with white ventral
surface. Black blotches around the free rear ends of the pectoral fins.
Undersides of the pectoral fin tips are black.
Genera Isurus
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Species (Isurus
oxyrinchus) Shortfin Mako - Seems to be dangerous, although
questionable.
Slender body, very hydrodynamic with a long and conical snout. Relatively
small pectoral fins. Large first dorsal fin, minute second one. Crescendic
caudal fin. Strong caudal fin on peduncle without secondary keels.
Coloration: Metallic blue coloration with white ventral surface.
The order Orectolobiformes - Carpet sharks: This order represents a
very diverse group with respect to size and shapes. It consists of 7 families
comprising 34 species. Carpet sharks have barbels and spiracles, holes
located behind their eyes, to suck in water. This order consists of 5 families
with more than 30 species. Assorted members of this group include species
such as whale sharks, nurse sharks, and zebra sharks. Typical species:
Whale shark (Rhiniodon typus)
Families: Nurse sharks, (Ginglymostomatidae) Genera Ginglymostoma
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Species (Ginglymostoma
cirratum) Nurse shark -Potentially dangerous. They are short-sighted
and can easely be scared, however harmless by nature.
Broad and flat head, with moderately long barbels. Mouth is well
in front of the very small eyes. Spiracles present. Two big and rounded
dorsal fins. Origin of first dorsal fin about opposite of pelvic fins.
Large, rounded pectoral fins. Very long caudal fin, over 1/4 of total body
length.
Coloration: Yellowish-brown to grey-brown. No conspicuous markings.
Families: Whale sharks, (Family - Rhiniodontidae, Genera - Rhiniodon)
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Species (Rhiniodon
typus) Whale shark - Harmless.
An unmistakable, huge shark with a broad, flat head. Truncated snout
and very big terminal mouth. Origin of first dorsal fin over the pelvic
fins. Second dorsal fin relatively small. Prominent ridges along the sides
with the lowermost expanding into the prominent keels on each side of the
lunate caudal fin. Prominent subterminal notch.
Coloration: Greyish to dark color with a unique checkerboard pattern
of light spots, horizontal and vertical stripes.
The order Heterodontiformes- Bullhead sharks; There are only 9 known
species of bullsharks These bizarre looking sharks possess strong spines
in front of both dorsal fins. As opposed to the other "spine-wearing" group,
the dogfishes, bullheads possess anal fins. As their name implies, their
heads look very dominant with big ridges above their eyes, and have a broad
snout with very large labial furrows. Based on their heterogeneous teeth
(their scientific name 'hetero-dontus' stands for different shaped teeth)
they are considered as primitive group. Members of this order live only
in the waters of the Pacific and Indian Oceans. Typical species: Port Jackson
shark (Heterodontus portusjacksoni)
The order Hexanchiformes - Frilled and cow sharks; This order is the
most ancient one. It consists of 2 families and 6 species. The most distinguishable
feature is the possession of 6 or even 7 gill slits. This is considered
a very primitive features, as most modern sharks possess only 5 gill slits.
Compared to sharks of other orders, frilled and cow sharks only have one
dorsal fin. These sharks have a widespread distribution and live preferably
in deeper waters. The knowledge about their biology is still fragmentary.
Typical species: Bluntnose sixgill shark (Hexanchus griseus)
The family Hexanchidae: - Genera Heptranchias
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Species (Heptranchias
perlo) Sharpnose sevengill shark - Harmless, although bites
when caught.
7 pairs of gill slits. Narrow, pointed head with large, green fluorescent
eyes. One dorsal fin. Long caudal peduncle.
Coloration: Greyish-brown on back, lighter ventral surface. Tip of dorsal
fin and caudal fin can be dusky, prominent in young, absent or faded in
adults.
Genera Hexanchus -
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Species (Hexanchus
griseus) Bluntnose sixgill shark - Seems to be harmless.
Broad-headed shark, with six gill slits and subterminal mouth. Small,
green fluorescent eyes. Only one dorsal fin. Its origin is over the free
rear ends of the pelvic fins. Short caudal peduncle.
Coloration: The dorsal surface is greyish-black or chocolate brown.
Lighter marking along lateral lines. Ventral surface greyish-white. Fins
with small white edges.
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Species (Hexanchus
vitulus) Bigeyed Sixgill shark - Probably harmless. Due to its
lifestyle encounters with humans are rare anyway. Lives preferably close
to the bottom down to depths of about 600m. This is a typical deepwater
species but has been found at the surface in tropical waters too.
lender body with a narrow head. 6 gill slits. Very big eyes. One dorsal
fin.
Coloration: Grey, with a white ventral surface.
Genera Notorynchus - Species Notorynchus cepedianus (Broadnose sevengill
shark) Wide-ranged in temperate waters. Western Atlantic: southern
Brazil, Argentina. Eastern Atlantic: Namibia to South Africa. Western Pacific:
Japan, Korea, China, Australia, New Zealand. Eastern Pacific: Canada to
California, Mexico, Peru, Chile.
Snorkeling 
Morning Coffee Break
