According
to the fossil record, hagfish have existed for over 300 million years,
which means they were already old when dinosaurs took over the world!
Found in relatively deep waters, these animals are sometimes called
slime eels, but they are not really eels, and actually, they may not
even be fish at all, according to some scientists. They are very bizarre
animals in all regards; they have a skull but lack a spine, and they
have two brains. Almost blind, they feed at night on the carcasses of
large animals (fish, cetaceans etc) which fall to the sea bottom. They
owe their slime eela nickname to the fact that they produce a slimey
substance to damage the gills of predatory fish; as a result, they have
virtually no natural enemies.
9. Lancetfish
The
lancetfish has a very obvious prehistoric appearance, with those
fierce-looking, sharp teeth on its jaws and the sail on its back,
reminiscent of that of some dinosaurs (although, in the lancetfish the
sail is actually an enlarged dorsal fin). Even its scientific name has a
dinosaurian sound to it (Alepisaurus ferox). Up to two meters in
length, this predator is found in all the oceans except for polar
regions; very voracious, it feeds on smaller fish and squid, and has
known to feed on members of its own species sometimes.
8. Arowana
Belonging
to the ancient group of the Osteoglossids, these fish already existed
in the Jurassic period. Today, they are found in the Amazon, and in
parts of Africa, Asia and Australia. Sometimes kept as exotic pets,
arowanas are voracious predators that feed on any small animal they can
catch, including birds and bats which they catch in mid flight (they are
able to leap up to 2 meters into the air). In China, arowanas are known
as dragon-fish due to their appearance, and they are thought to be
harbingers of good luck.
7. Frilled Shark
This deep
sea predator, one of the most primitive sharks alive today, is a relic
from the Cretaceous period, when dinosaurs ruled the Earth. Seldom seen
alive, and only recently filmed for the first time, the frilled shark
can grow up to 2 meters (with females being larger than males) and they
live in deep waters, where they feed mostly on squid. They are not
dangerous to humans, and as a matter of fact, most frilled sharks spend
their whole lives without seeing a human being. Only dead or dying
specimens are usually seen and recorded by fishermen or scientists.
6. Sturgeon
Another
survivor from the age of dinosaurs (they were already around in the
early Jurassic), the sturgeon is well known for being one of the main
sources of caviar (which is made out of their roe or egg masses); due to
overfishing, these magnificent, armored fish are sadly endangered
nowadays. The largest sturgeon species can grow up to 6 meters long,
being as large as most great white sharks; they feed on small animals
from the sea bottom and pose no danger to humans, unless provoked
(although they are so big that they have hurt, and even killed, people
unintentionally by leaping out of the water and landing on boats!)
5. Arapaima
A close
relative to the arowana (see #8), the Amazonian arapaima is sometimes
considered to be the largest freshwater fish in the world. According to
early descriptions, it could grow up to 4.5 meters long, but today,
enormous individuals like these are seldom found and most adult
arapaimas average 2 meters long. These slow moving predators feed on
smaller fish, crustaceans and whatever small animal they can fit in
their mouth. An interesting trait of this fish is that it needs to
breath oxygen from the air, like a cetacean, in order to survive.
Arapaimas pose no danger to humans and are often hunted for their meat;
unfortunately, they are very scarce nowadays. Although the arapaima
seemingly appeared in the Miocene period, it belongs to a much older
family, the Osteoglossidae, and therefore its origins can be traced back
to the age of dinosaurs.
4. Sawfish
This
critically endangered animal is a survivor from the Cretaceous period,
and can be found both in saltwater or in rivers and creeks, and has been
found up to 100 kms inland. Up to 7 meters in length, sawfish may look
like sharks but are actually more closely related to rays. Their saw is
both a weapon and a sensory organ, covered on electro-sensitive pores
which allow it to sense prey despite its terrible eyesight. Although
usually peaceful, the sawfish can become extremely dangerous if
provoked. Due to an extraordinary fossil, we know that gigantic,
prehistoric sawfish were probably a staple food for the largest
carnivorous dinosaur, Spinosaurus, as a vertebra from the fish was found
stuck between the dinosaur's teeth.
3. Alligator Gar
This
formidable, thick scaled predator is found in the southern US and
northern and eastern Mexico, being the largest freshwater fish in North
America (although it sometimes wanders into the sea). It can grow up to 4
meters long and weigh up to 200 kgs (440lbs). Gator gars are so called
because of their reptilian appearance and long jaws, armed with a double
row of sharp teeth. They are voracious ambush predators and have been
known to bite humans on occasion, although no confirmed deaths due to
alligator gars have been recorded to date. Gars are among the oldest
fish alive today; their origins can be traced back to the Cretaceous
period.
2. Polypterus Senegalus
These
african fish are often called dinosaur eels, due to their reptilian
appearance and serrated dorsal fin, reminiscent of some dinosaurs spiked
backs. They are not really eels, but members of the bichir family.
Bichirs were already around in the Cretaceous, so the dinosaur part of
their name is actually fitting in a way. Although often sold as exotic
pets, dinosaur eels are prone to escaping their fish tanks. They can
survive out of the water for long periods of time as long as their skin
remains wet, which enables them to wander far away from their tank.
1. Coelacanth
The
Coelacanth is the most famous of all living fossils and deserves to be
#1 in this list, because it is the best example of a Lazarus taxon, this
is, animals that were supposed to be long extinct and are unexpectedly
found to be alive. Coelacanths were supposed to have become extinct in
the Cretaceous period, along with the dinosaurs, but in 1938, a live
specimen was caught in South Africa. Since then, more specimens have
been seen and photographed, and a second coelacanth species was even
found in Indonesia in 1999. Coelacanths are large predators, up to 2
meters long; they feed on smaller fish, including small sharks, and are
usually found in deep, dark waters. Although rarely captured and
consumed due to their horrible taste, coelacanths are critically
endangered nowadays.