Records in the fish world
Stéphan G. Reebs
Université de Moncton, Canada
2007
Shortest
lived vertebrate (not just fish): The
pigmy goby Eviota sigillata
59 days after hatching.
These tiny fish live on the Great Barrier Reef
and other reefs in the Pacific and Indian oceans. They spend the first three
weeks of their life as larvae in the open ocean and then they settle on the
reef. They mature within two more weeks. In the next three and half weeks, the
female can produce up to three clutches of eggs (about 400 eggs in total). The
male stands guard over the eggs and fans them. Then they disappear. The pigmy
goby’s fast and furious lifestyle may be an adaptation to high predation rates
which decrease an adult’s chance of living long anyway. Indeed, the reason why
no fish over 59 days of age (as determined by daily growth rings in the
otoliths, or ear stones) has ever been found is probably that they are systematically
picked off by predators.
Runner-up: The turquoise killifish Nothobranchius
furzeri, an extremely
rare fish that lives in temporary pools in Africa, has a maximum lifespan of 84
days post-hatching, even in the absence of predators in the lab. Most of the
fish’s lifecycle is spent as eggs that are encased in mud for 5-7 months and
hatch only during seasonal rains. Pools exist only for several months, which explains
the brevity of the post-hatching life.
Source: Guinness Book of Records; Depczynski,
M., and Bellwood, D.R., 2005, Shortest recorded vertebrate lifespan found in a
coral reef fish, Current Biology 15, R288-R289; Valdesalici, S. and Cellerino, A.,
2003, Extremely short lifespan in the annual fish Nothobranchius furzeri, Proceedings of the Royal Society
of London B 270 (Suppl. 2), S189-S191.
Longest
lived fish: The rougheye rockfish Sebastes
aleutianus
140
years
The age of fish is usually determined by taking
the fish’s otoliths (ear stones) and counting its growth rings, as in trees.
This technique crowns the rockfishes as the Methuselah of the fish world. Other
long-lived scorpaenid rockfishes are S. borealis (120 years) and S. alutus (90 years). All these species live
in the cold waters of the northeastern Pacific.
Other notables: Several sturgeon species
include centenarians (i.e., Huso huso, Acipenser transmontanus, Acipenser sturio). The Guinness Book of Records also
mentions a female European eel (Anguilla anguilla) named Putte which was 88 years old
when she died at Hälsingborg Museum in Sweden in 1943.
The longest-living shark is the spiny dogfish, Squalus
acanthias, with a
lifespan upward of 70 years. They become sexually mature around the age of 20
years.
Source: Helfman, G.S., Collette, B.B., and
Facey, D.E., 1997, The diversity of fishes, Blackwell Science, Malden; Fish Base www.fishbase.org;
Guinness Book of Records.
Smallest
fish (vertebrate, even): 3 candidates
Paedocypris
progenetica, female
7.9 mm long
Photocorynus
spiniceps,
parasitic male 6.2 mm long
Schindleria brevipinguis, less than 2 mg live weight
You seldom hear fishermen arguing about who’s
got the smallest fish. Good thing, because this category could indeed lead to prolonged
(but probably good-natured) exchanges. It is not clear which species should win
the title of smallest fish, and it probably depends on what you mean by
“smallest”.
Paedocypris progenetica was described for the first time in
a 2006 publication. A relative of the carp, it lives in slow-moving, acidic waters
in the peat swamp forests of Sumatra. The maximum length is 10.3 mm (0.4 inch) and
females can reach maturity at 7.9 mm (0.3 in). Many bones are absent from the
skull and jaws, and the female can carry only a few eggs. Peat swamps often
harbour miniature fish species. Small size may be an adaptation to survive in
shallow pools, in burrows, or even in moist peat when water levels fall.
Deepsea anglerfishes of the suborder
Ceratioidei are characterized by an extreme sexual dimorphism. The males are
tiny and they attach themselves to the body of the much larger females (perhaps
a reflection of how hard it is to find a mate in these widely scattered fishes). In some species the circulatory systems
of the male and female fuses so that the male becomes dependent on the female
for nutrition. Such a male can be said to be parasitic on the female. He is
kept around solely for his eventual contribution to reproduction. Essentially,
he is little more than a living gonad. In the species Photocorynus spiniceps, a 6.2 mm-long (0.24 inch) mature
male has been found attached to a 46 mm (1.8 inch) female. Can a species claim
the title of smallest fish if only half of its members qualify?
The stout infantfish Schindleria
brevipinguis is a
relative of gobies and so far it is has been found only in the Great Barrier
Reef of Australia. Females and males reach sexual maturity by 7-8 mm (0.27-0.31
inch) and 6.5-7 mm (0.25-0.27 inch) respectively. The largest specimen ever
collected was 8.4 mm long (0.33 inch). Adults are paedomorphic – that is,
they resemble juveniles, hence the name infantfish. They lack features such as
teeth, scales, pigment and pelvic fins. Because this species is more slender
than the two candidates above, it is probably lighter. A formalin-preserved
specimen weighed only 0.7 mg; I am aware of no measurements on live specimens,
but based on measurements on other similar-looking species, a live stout
infantfish probably would not exceed 2 mg (that’s 0.00007 ounce).
At least three species vie for the title of smallest
shark. There is the male Spined Pigmy Shark Squaliolus laticaudus, which can mature when about 15 cm
(6 inches) long and whose maximum recorded length is 22 cm (8.7 inch). The
Cylindrical Lanternshark Etmopterus carteri and the Dwarf Lanternshark Etmopterus
perryi mature
between 15-20 cm, giving birth to live young, and they get no longer than about
21 cm.
Source: Kottelat, M., Britz, R., Hui, T.H., and
Witte, K.-E., 2006, Paedocypris, a new genus of Southeast Asian cyprinid fish with a remarkable sexual
dimorphism, comprises the world’s smallest vertebrate, Proceedings of the Royal
Society of London B 273, 895-899; Pietsch, T.W., 2005, Dimorphism, parasitism,
and sex revisited: modes of reproduction among deep-sea ceratioid anglerfishes
(Teleostei: Lophiiformes), Ichthyological Research 52, 207-236; Watson, W., and
Walker, H.J. Jr., 2004, The world’s smallest vertebrate, Schindleria
brevipinguis, a new
paedomorphic species in the family Schindleriidae (Perciformes: Gobioidei),
Records of the Australian Museum 56, 139-142; Compagno, L., Dando, M., and Fowler,
S., 2005, Sharks of the World (Princeton Field Guides series), Princeton
University Press, Princeton.
Largest fish: Whale
shark Rhincodon typus
34,000
kg, 20 m long (about 75,000 pounds, 65 feet long)
This huge shark feeds mostly on plankton and small fishes. It is harmless
to humans. A length of 20 m is exceptional; specimens are rarely longer than 12
m (which is still impressive).
In 2006, researchers present at the International Whale Shark Conference in
Perth, Australia, reported that the largest whale sharks are getting scarce.
Based on log books filled out by ecotourism operators at Ningaloo Reef, the
average length of whale sharks has declined from just over 7 m in 1995 to 5.5 m
in 2006. Over-fishing in unprotected waters and collisions with sea vessels may
have been killing the oldest and largest members of the population.
The largest fish species in the world are all cartilaginous (their skeleton
is made of cartilage rather than bone): gold medal to the whale shark, silver
to the basking shark, bronze to the great white shark. The also-rans are also
cartilaginous: the Greenland shark, the manta ray, the sawfish, the six-gill
shark, and the tiger shark. See the next entry for more on cartilage and body
size.
Source: Fish Base www.fishbase.org
Largest
bony (teleost) fish: Ocean Sunfish Mola mola
2,300
kg, 3.3 m long (about 5,060 pounds, 10 feet long)
Molas have a funny shape. They are rectangular
in side view and lack a true tail. Their pseudo-tail is made up of dorsal and
anal fin rays. They attain their big size on a steady diet of jellyfish.
Interestingly, for a “bony” fish the ocean
sunfish has a rather large number of cartilaginous elements in its skeleton. The
second largest “bony” fish, the great (or beluga) sturgeon Huso huso (2070 kg, 5 m long) also has a
skeleton made mostly of cartilage.
The thing with bone is that it is denser than
water and makes a fish sink. Because of geometrical considerations, as body
size increases, the weight of bones increases more quickly than the lift
generated by the fish’s fins and often-flat body. Above a certain size, sinking
cannot be efficiently prevented.
Now, cartilage is also denser than water, but
not as much as bone. Having a skeleton made up of cartilage rather than bone
means you can grow to a larger size before you reach the point at which sinking
cannot effectively be counteracted by lift.
The largest fishes with skeletons entirely made
up of bones are the marlins. Many species are of similar size. The blue marlin Makaira
nigricans can be
used as an example. Its maximum dimensions are 5 m in length (16.5 feet) and 820
kg in weight (1808 pounds).
How can whales prevent sinking despite their
huge bony skeletons, you will ask? Whales are mammals; they have air-filled lungs
which act as floatation devices.
Source: Fish Base www.fishbase.org
; Summers, A., March 2007, No bones about ‘em, Natural History 116(2): 36-37.
Largest freshwater fish: Many
candidates, depending on whether you go for length or weight or a combination
of both. Sturgeons that move between freshwater and saltwater are not included
in the following list.
The
Wels catfish Siluris glanis
300
kg, 5 m long (660 pounds, 16.5 feet)
The Mekong giant catfish Pangasianodon gigas
350 kg, 3 m long (770 pounds, 10
feet)
The Chinese swordfish Psephurus
gladius
300 kg, 3 m long (660 pounds, 10
feet)
The giant pangasius Pangasius
sanitwongsei
300 kg, 3 m long (660 pounds, 10
feet)
The giant barb Catlocarpio
siamensis
300 kg, 3 m long (660 pounds, 10
feet)
The freshwater whipray Himantura
chaophraya
600 kg, 2.4 m wide
The arapaima, or pirarucu, Arapaima gigas
200 kg, 4.5 m long (440 pounds, 15
feet)
The kumakuma Brachyplatystoma
filamentosum
200 kg, 3.6 m long (440 pounds, 12
feet)
The Nile perch Lates niloticus
200 kg, 1.9 m (440 pounds, 6.3 feet)
The Wels catfish is a European predator; it
feeds on other fishes, crayfish and even on ducks (a reversal of the normal
food chain). The giant pangasius will not say no to the carcass of a dog, and
this item is sometimes used as bait by fishers. Monkey parts have been found in
the stomach of kumakuma, a South American catfish. Not all giants are predatory,
however; the Mekong giant catfish, for example, is herbivorous.
The arapaima lives in the Amazon River basin.
Like a few other fishes (see page on oxygen), this fish is an obligatory air
breather. It must take gulps of air at the surface to obtain enough oxygen to
survive. Surprisingly for a fish, it will drown if it cannot reach the surface.
The noise it makes when taking gulps can be heard over fairly long distances. All this makes it fairly easy to find
and harpoon, and large individuals are becoming rare. The Mekong giant catfish
and Chinese paddlefish are also rare.
Source: Fish Base www.fishbase.org
; Stone, R., June 2007, The last of the leviathans, Science 316, 1684-1688
Longest
bony (teleost) fish: Oarfish
(King of herrings), Regalecus glesne
11
m long (36 feet)
The oarfish (aka King of herrings) has a ribbon-like body that has been
reliably documented to grow to 11 m in length. It has no tail but a dorsal fin
runs the whole length of the body. It lives at great depths in the Pacific,
Atlantic, and Indian Oceans. Dead specimens are occasionally cast up on
beaches. Despite being toothless, it feeds on other fishes and on squid,
presumably catching them by sucking them in. This fish may be behind some of
the “sea-monsters” sightings. The name “oarfish” comes from its two long pelvic
fins.
Source: Fish Base www.fishbase.org
Largest
carnivorous fish: Great
white shark Carcharodon carcharias
3,400
kg, 7.2 m
Greenland
shark Somniosus microcephalus
775
kg, 7.3 m
Most people would object to the Greenland shark being included here. It is
little known and rather sluggish, not your typical image of a fierce predator.
But they do feed on other fishes, and they get a bit longer than great whites,
so…
Source: Guinness Book of Records; Fish Base www.fishbase.org
Most fecund vertebrate (not just fish): Ocean
sunfish Mola mola
Up to 30 million eggs, each 2 mm in diameter, at a single spawning
It is not surprising that the largest “bony” fish should also be the most fecund,
as adult size and egg number are positively correlated across and within
species.
The largest cartilaginous fish, the whale shark, is no slouch itself: only
one pregnant female has ever been dissected and she had a litter of 300 pups
inside of her (like many sharks, the whale shark is ovoviviparous: eggs hatch
and young develop inside the mother).
Source: Guinness Book of Records.
Fastest
fish: The sailfin Istiophorus
platypterus
109
km/h (68 mph)
Like its cousins the marlins, this oceanic fish
pursues other fast swimmers such as mackerels. Its record swimming speed comes
from one fish hooked by a sport fisherman that took out 300 feet of line in 3
seconds. For comparison, the fastest land vertebrate, the cheetah, runs at 60
mph tops.
The shortfin mako Isurus oxyrinchus is presumed to be the fastest
swimming shark, with a burst speed of about 74 km/h (46 mph). It can jump up to
6 m (20 ft) in the air.
Source: Guinness Book of Records (sailfin),
Wikipedia (shortfin mako).
Deepest-living
fish: The cusk-eel Abyssobrotula galatheae
8,370
m (27,455 feet)
A
20 cm long Abyssobrotula galatheae (family Ophidiidae) has been collected from the
Puerto Rico Trench at a depth of 8,370 m.
Source: http://amonline.net.au/fishes/faq
Most venomous
fish: The
estuarine stonefish Synanceia horrida
“Most venomous” is hard to define. But the Guinness Book of Records states
that this stonefish, which inhabits coastal reefs and estuaries from India to
Australia, has the largest venom glands of any known fish. The venom is delivered
through the spines of the dorsal fin, which can pierce human skin. A single prick
can be fatal. At the very least, the pain caused by the venom is said to be
excruciating.
It is estimated that at least 200 fish species are venomous (among them:
lionfishes, catfishes, scorpionfishes, weeverfishes, toadfishes, surgeonfishes,
rabbitfishes, stargazers, pufferfishes, stingrays, some sharks even, and stonefishes
of course). A paper published in 2006 argued that this number should be bumped
up to 1200, based on an analysis of genomes and evolutionary trees. This is
quite an extraordinary number, but it must be put in context: there are over
24,000 species of fishes in total.
A related category could be “most poisonous fish to eat” (“venomous” means
the poison is injected through a spine or a fang; “poisonous” means the poison
in the flesh and so it takes effect only when the fish is eaten). Some pufferfishes
(family Tetraodontidae) contain the powerful poison tetrodotoxin in their
ovaries, liver, intestines, and skin. In Japan, pufferfish (minus the offensive
organs) is served as “fugu”. Eating fugu is flirting with death: if the cook made
a mistake in the preparation, you can become severely ill or even die from
tetrodotoxin poisoning.
Source: Guinness Book of Records; Smith, W.L., and Wheeler, W.C., 2006,
Venom evolution widespread in fishes: a phylogenetic road map for the bioprospecting
of piscine venoms, Journal of Heredity 97, 206-217.
Longest
parental care in fish: The Magellan plunder fish Harpagifer
bispinis
4-5
months
This fish is found in shallow rubble coves
along the Antarctic Peninsula. The female prepares a nest site by cleaning a
patch of ground. After her eggs are laid and fertilized, she remains on the
nest, cleaning the eggs and chasing predators until hatching occurs 4 to 5
months later. This is the longest brooding period reported for any fish.
Source: Daniels, R.A., 1979, Nest guard
replacement in the Antarctic fish Harpager bispinis: possible altruistic behavior,
Science 205, 831-833.
Best
shot: The
archerfishes Toxotes spp.
The archerfishes are found in the tropical
mangrove swamps of India and Australasia. They take aim at insects that sit on
plants above the surface, squirt a jet of water at them, and grab them after
the bugs have been knocked off into the water. The jet of water is formed by
the action of the tongue, which presses against a groove in the roof of the
mouth. Some archerfish can score a direct hit up to 1.5 m above the water
surface (though not necessarily on the first try). They use more water (which gives more force to the impact)
when aiming at larger prey. They can even learn to shoot at moving targets,
either through practice or by observing an experienced individual in action.
Archerfish can be kept in aquaria, and they are not beyond shooting jets of
water at the eyes of people who blink at them.
Source:
Schlegel, T., Schmid, C.J., and Schuster, S., 2006, Archerfish shots are
evolutionarily matched to prey adhesion, Current Biology 16, R836-R837;
Schuster, S., Wöhl, S., Griebsch, M., and Klostermeier, I., 2006, Animal
cognition: how archer fish learn to down rapidly moving targets, Current
Biology 16, 378-383; Dill, L.M.,
1977, Refraction and the spitting behavior of the archerfish (Toxotes
chatareus), Behavioral Ecology and
Sociobiology 2, 169-184.
Largest
shoal: Millions
and millions of fish!
A 2006 report in the journal Science (3
February 2006, Volume 311, pages 660-663) shows images of huge shoals taken
with a remote sensing technique near the edge of the continental shelf off the
east coast of North America. The shoals – most likely made up of Atlantic
herring, scup, hake, and black sea bass – were said to contain “tens of
millions” of fish and stretched for “many kilometers”. Changes in shoal shape could be followed
throughout the day with this new technique.
The web site http://www.sealife.fi/page.php?page_id=82 also mentions a record shoal of 3 billion
herrings, but lists no source.
Most abundant vertebrate (not just fish) genus: Bristlemouths
of the genus Cyclothone
On its page about the family Gonostomatidae
(the bristlemouths), Fish Base (www.fishbase.org) states that “Cyclothone, with 12 species, occurs in
virtually all seas including the Antarctic and has, along with Vinciguerria, the greatest abundance of individuals
of any vertebrate genus in the world.” Bristlemouths live in the deep sea. Vinciguerria, for its part, is a genus of
lightfishes (family Phosichthyidae) which also live in the deep sea.
Most vocal: The
plainfin midshipman Porichthys notatus
It is generally overlooked by the general public that many (in fact,
probably most) fishes can produce underwater sounds by vibrating the
swimbladder, by rubbing bones or teeth together, or by snapping tendons. Like
birds and mammals, fishes vocalize to advertise territories and mating
availability, intimidate adversaries, and startle predators.
Among some of the fish groups recognized for their chatty tendencies are
the toadfishes (family Batrachoididae). Of these, the males of the plainfin
midshipman are worthy of attention. During the reproductive season, they “hum”
to attract females. They do this by vibrating their swimbladder. A single
individual can hum for as long as an hour without pause, the longest uninterrupted
fish sound ever reported. These fish are nocturnal like frogs, and as in frogs
their combined output can create quite a racket. In San Francisco Bay,
houseboat dwellers sometimes complain that they cannot sleep because they can
hear the fish’s chorus through the bottom of their boats.
Another vocal group is the triggerfishes (family Balistidae). Triggerfishes
are so named because their first dorsal spine is particularly strong and can be
locked in an erect position, like a trigger. They are also quite vociferous,
and the native Hawaiian name for two of the triggerfishes that live around the
islands is humuhumu nukunuku apua’a, “the fish that sews with a needle and grunts
like a pig”.
Other incorrigible blabbermouths include the aptly named croakers (family
Scianidae) and grunts (family Haemulidae), the catfishes (order Siluriformes),
the clownfishes and damselfishes (family Pomacentridae), and the gouramis
(anabantoids), to name but a few.
Source: Helfman,
G.S., Collette, B.B., and Facey, D.E., 1997, The diversity of fishes, Blackwell
Science, Malden; Ibara, R.M., Penny, L.T., Ebeling, A.W., van Dykhuizen, G.,
and Caillet, G., 1983, The mating call of the plainfin midshipman fish, Porichthys
notatus, In:
Predators and prey in fishes (D.L.G. Noakes et al., eds.), Dr. W. Junk, The
Hague.
Best
hearing at high frequencies: The American shad Alosa
sapidissima
180,000
Hz
Ultrasound is defined as any sound frequency above the maximum detectable
by the human ear (20,000 Hz). Bats, dolphins and moths are animals that can
detect ultrasound. In bats and dolphins, this ability is part and parcel of
their echolocation system: they both produce and hear ultrasound. In moths,
which are prey to bats, ultrasound detection is simply a way to detect the
proximity of a predator. One might expect that some of the fish species on
which echolocating dolphins feed would also have evolved ultrasound detection,
like moths did. And indeed, several have: the Atlantic cod Gadus morhua (which can hear sounds up to 34,000 Hz in
frequency), the Gulf menhaden (80,000 Hz), the alewife (128,000 Hz), the
blueback herring (140,000 Hz), and the American shad (180,000 Hz).
Source: Higgs, D.M., 2004, Neuroethology and sensory ecology of teleost
ultrasound detection, pp. 173-188 in (von der Emde, G., Mogdans, J., and
Kapoor, B.G., eds.) The Senses of Fish: Adaptations for the Reception of
Natural Stimuli, Kluwer Academic, Boston;
Mann, D.A., Lu, Z., and Popper, A.N., 1997, A clupeid fish can detect
ultrasound, Nature 389, 341.
Finest
sense of taste: Channel
catfish Ictalurus punctatus
Catfishes have taste receptors not only in their
mouth but also on their body, especially on the barbels. A 1975 paper reported
that the barbel of a channel catfish could detect some amino acids at
concentrations as low as 10-9 to 10-11 M, “the lowest
electrophysiological thresholds reported for taste in any vertebrate”.
Source: Caprio, J., 1975, High sensitivity of
catfish taste receptors to amino acids, Comparative Biochemistry and Physiology
52A, 247-251.
Most
electric: Electric
eel Electrophorus electricus
The electric eel of the Amazon and Orinoco
rivers can generate electric pulses of about 500 volts (the Guinness Book of
Records says 650 volts) at 1 amp. That is enough to stun a prey or discourage a
predator, but it will not kill a person. Second place goes to the electric
catfishes (family Malapteruridae) of Africa, with 300 volts, while third place
belongs to the electric ray Torpedo torpedo of the Mediterranean, with 50 volts.
Stargazers (family Uranoscopidae) can also discharge pulses of electricity up
to 50 volts.
Going from production to perception: some fish
can detect the very weak electric fields that are generated by the living
tissues of other fishes. Sharks use this ability to find prey hidden in sand.
Many sharks and skates can detect voltage gradients as small as 0.01 microvolt
(that is, ten billionth of a volt) per centimeter, the greatest electrical
sensitivity known in the animal kingdom.
Source: Reebs, S.G., 2001, Fish Behaviour in
the Aquarium and in the Wild, Cornell University Press, Ithaca.
Most
sensitive to barometric pressure: Weatherfishes,
sharks
I don’t think any contest has ever been held to
determine the winner of this category, but it is interesting simply to mention
that some fish are sensitive to barometric pressure.
Weatherfishes (loach family, Misgurnus spp.) become restless when
atmospheric pressure drops before a storm (hence their name).
Several hours before tropical storm Gabrielle
struck Florida’s Gulf Coast on September 14, 2001, all the juvenile blacktip
sharks living in a shallow coastal nursery moved to deeper and safer waters
offshore. The only environmental cue that coincided with the departure time was
a sudden drop in barometric pressure. The first sharks started to leave once
the pressure had dropped by 4 mb, and by the time the last one was on its way
out the pressure had dropped by 13 mb. The sharks returned to the nursery after
the storm passed.
Source: Heupel, M.R., Simpfendorfer, C.A., and
Hueter, R.E., 2003, Running before the storm: blacktip sharks respond to
falling barometric pressure associated with Tropical Storm Gabrielle, Journal
of Fish Biology 63, 1357-1363.
Fastest
vertebrate muscle contraction: The
oyster toadfish Opsanus tau
In the oyster toadfish (same family as the
plainfin midshipman, see Most Vocal Fish above), the swimbladder can vibrate
and produce a “boatwhistle call”. The vibration comes from muscles that can move
at a rate of 200 individually defined contractions per second, a vertebrate
record. Second place goes to the shaker muscles of the rattlesnake’s tail,
which contract at only half that rate.
Source: Reebs, S.G., 2001, Fish Behaviour in
the Aquarium and in the Wild, Cornell University Press, Ithaca.
Most
roundabout digestive system: The
pirate perch Aphredoderus sayanus
The anus of this fish is not near the anal fin,
as in any self-respecting fish. Instead, the anus opens up in the throat
region, close to the mouth, for reasons unknown.
Source: Helfman, G.S., Collette, B.B., and
Facey, D.E., 1997, The diversity of fishes, Blackwell Science, Malden.
Biggest mouth (relative to body size): Gulpers
(Saccopharyngidae)
Swallowers (Eurypharyngidae)
The hinged jaws of these deep-sea dwellers
allow their mouth to expand to a volume 10 times bigger than the volume of the
rest of the body. It has been said
of these fishes that they were “perhaps the most anatomically modified of all
vertebrate species” (Page 115 in Nelson, J.S., 1994, Fishes of the World, 3rd
ed., John Wiley and Sons, New York). Not only do they have huge mouths, they
also lack scales, pelvic and pectoral fins, ribs, gas bladders, and a number of
bones.
Other deep-sea fish, such as dragonfishes,
viperfishes, sabertoothfishes, and ceratioid anglerfishes can also swallow prey
bigger than themselves (in fact, three times bigger, in the case of some
anglerfishes). It looks like food is so scarce in the deep sea that these
fishes can’t afford to pass up a meal just because it might be too big to
swallow. Large mouths have evolved as a result.
Source: Helfman, G.S., Collette, B.B., and
Facey, D.E., 1997, The diversity of fishes, Blackwell Science, Malden.
Longest
tail: Thintail
thresher shark Alopias vulpinus
3
m (10 ft), half of the total body length
Thresher sharks swim around or into dense fish
shoals and use their long tail to whack at prey.
Largest
difference between male and female: The anglerfish Ceratias holboelli
Female can be 60 times longer
and 500,000 times heavier than male
As you already know, anglerfishes of the suborder
Ceratioidei live in the deep sea. The males are dwarfed and attach themselves
(temporarily or permanently) to the bodies of the females. See Smallest fish
category above.
Source: Pietsch, T.W., 2005, Dimorphism,
parasitism, and sex revisited: modes of reproduction among deep-sea ceratioid
anglerfishes (Teleostei: Lophiiformes), Ichthyological Research 52, 207-236.
Slimiest: Hagfishes
(family Myxinidae)
Hagfishes are also called slime eels. They have
70-200 pairs of slime glands on their sides and belly. These glands produce a
protein and a carbohydrate that combine with water to form mucus. A 50-cm (20
in) hagfish can fill an 8-liter bucket (2 gallons) with slime in a few minutes.
The mucus is extremely gooey and may have an anti-predator function. Slime eels
can rid themselves of their own mucus by tying a knot in their body and then
sliding the knot forward, squeezing the mucus into a mass from which the fish
backs out.
Also worth mentioning are some species of
parrotfish that secrete a mucus envelope around themselves during their “sleep”
at night. Except for a small hole through which they can breathe, the envelope
completely surrounds the body. It may act as a barrier to the diffusion of
odours, making the fish less detectable by nocturnal predators such as moray
eels. (See page on sleep)
Source: Helfman, G.S., Collette, B.B., and
Facey, D.E., 1997, The diversity of fishes, Blackwell Science, Malden.
Most inflatable (and most
spherical): Porcupinefish,
balloonfish, pufferfish (families Tetraodontidae and Diodontidae)
When threatened, these fish pump water into their greatly extendable
stomach. In about 15 seconds the whole body becomes almost as round as a ball.
Inflation has become the sole function of these fish’s stomach; food passes
through it undigested and goes straight to the intestine. The skin is also
remarkably stretchable and is not attached to the underlying musculature. Body
scales are modified as spines (these could in fact earn the title of longest
modified body scales in any fish) and these spines are normally held against
the body, pointing backwards. But when the body is inflated the spines stick straight
out and the fish looks like a burr. Inflation and erect spines make the fish
unswallowable.
Source: Helfman, G.S., Collette, B.B., and
Facey, D.E., 1997, The diversity of fishes, Blackwell Science, Malden.