The sea lamprey (Petromyzon marinus)

The sea lamprey doesn't look like a fish at all! In fact, this primitive fish doesn't even have bones. The sea lamprey has a long, slender eel-like body, with a sucker disc mouth. This parasitic fish attaches its mouth onto unsuspecting victims such as lake trout or whitefish, and literally sucks the life out of them! Since its introduction into the Great Lakes in the 1930's, this species has caused many problems for the commercial and recreational fishing industries and some 10 million dollars are spent each year to control them.

2.Piscine Pinocchio 

The longnose gar (Lepisosteus osseus)

 

 

This freshwater fish is curious looking. Although this fish is no liar, it has a monstrous snout with many sharp teeth. Its fins occur far back on its very long, cylindrical body, making it efficient at darting out quickly to capture prey. This ancient fish is also well protected by heavy, armored scales, called ganoid scales.

 3.Hey butt-head!!

 The pirate perch (Aphredoderus sayanus)

 The pirate perch is the only member of its family and is native to the southern portions of the Lake Erie and Ontario basins. It has a large mouth, rough scales on both the head and body and one dorsal fin with spines and rays. So far, the pirate perch sounds like many other fish, but these fish have a unique characteristic: their anus is on their throat! When they are juveniles, the anus is found in a normal position, in front of the anal fin, but as they grow, their anus migrates anteriorly until it ends up on the throat,between the gill membranes.

4.Cross dressing fish!

The bluegill sunfish (Lepomis macrochirus)

What do sneakers and satellites have to do with fish? Although the bluegill sunfish is very common to the Great Lakes region, its reproductive strategies are not so common and have been the focus of many scientific studies. During mating, large, dominant males defend a nest to attract a female, while small "sneaker" males hide nearby. When until a female enters the nest of a dominant male he rushes in, discharging sperm as the eggs are released, in an attempt to gain fertilizations. "Satellite" males actually resemble females and attempt to join a mating pair in a nest to obtain fertilizations. Such alternative reproductive strategies have been described in other sunfish and in fish species of other families.  

5.Obsessively clean!

The fantail darter (Etheostoma flabellare)

In many fish, it is the male rather than the female that puts more energy into breeding. Reproduction is important to the male fantail darter and he takes his business seriously! He sets up a breeding territory, readies it for the female and sticks around after breeding to guard the eggs. The males have fleshy, round tips on their dorsal fin spines which are used to clean both the eggs, and the surface of a rock where they will be laid. Now that's clean! During the breeding season, males are particularly slimy. It is thought that the mucous contains anti-bacterial and anti-fungal agents which protect the eggs from infections.  

6.Mr. Freeze...

The winter flounder (Pleuronectes americanus)

 

 In the winter, water temperatures in the Arctic can drop below -1.8 OC. Just as we use antifreeze in our cars to avoid freezing, the winter flounder fills its blood with up to 3% antifreeze! They save precious energy in the summer by reducing the production of the antifreeze, which also allows the blood to carry more oxygen and nutrients.

 7.Deceptive fish!

 Lanternfishes (Family Myctophidae)

 

 

Lanternfishes are deep sea fish, found in all the oceans of the world. They swim in such large schools that sonar pulses from the navigational equipment of boats often bounce off of their swim bladders, giving the impression of a false ocean bottom!

 8.Fish with flashlights!

 Lanternfishes (Family Myctophidae)

 

The lanternfishes are a large family of small fishes, found in the deep, dark, marine waters of the Arctic, Atlantic and Pacific Oceans. These fish are well named because they have special light emitting organs called "photophores" lining their head and body. These tiny flashlights not only allow them to see better, they attract their favorite prey: tiny copepods and ostracods. The number and pattern of photophores are used to identify the various species of lanternfishes.

 9.Super dad!

 Sticklebacks (Family Gasterosteidae)

 

 

Sticklebacks occur in both marine and freshwater environments in every region of Canada. Their common name is appropriate because of their well  developed spines with triangular membranes sticking out from their back. They not only have unique spines, but sticklebacks have unique reproductive habits. The male stickleback constructs a nest on grass and stems on the bottom and uses grass, fibres, algae and secretions from his own kidney to bind the nest materials together. The male spends a significant amount of time and energy enticing females to enter his nest and lay eggs, but soon after the egg laying, he drives her away to attend to his future offspring. The male remains with the nest, guarding the eggs and supplying them with oxygen by fanning them until they hatch.

10.More than a mouthful!

Sloane's Viperfish (Chauliodus sloani)

 

 

Sloane's viperfish is quite a small fish, but it has a HUGE appetite! Its teeth are so large, that it wouldn't be able to ingest large prey if it was like other fish. Luckily, this fish has some unique jaw modifications. As its mouth opens, the skull and the attached vertebrae rotate upwards and the hinge of the jaw is pushed forward. At the same time, the operculum separates from the gills and moves upwards with the skull. As if that weren't enough, its heart and associated arteries are displaced downwards when prey is swallowed. This adaptation allows viperfish to get large prey past their fangs.

11.Hot stuff!

 

 

Tunas, thresher sharks, and mackerel sharks are cruising fish. Theymaintain high levels of activity for prolonged periods and are able to keep their muscles above the water temperature! Bluefin tuna muscles are constantly between 28 oC and 33 oC, even though they swim through waters that are as cold as 7 oC, or as warm as 30 oC! In most fish, blood flows from the body to the heart and is oxygenated by the water in the gills. After oxygenation, the dorsal aorta carries the cold blood down the center of the body, keeping the core temperature of the fish approximately the same as the water. Tunas, threshers and mackerel sharks have a slight modification! After oxygenation, cold blood leaves the gills and travels down the periphery of the body. As it passes into the core of the fish it goes through a counter-current exchange system where the warm blood leaving the muscles transfers its heat to the cold blood coming into the core. This counter-current exchange allows the internal temperature to remain constant.

 12.2 for 1!

 

 

A hermaphrodite is an organism that has both male and female reproductiveorgans. There are many types of hermaphrodites: Simultaneous hermaphrodites produce sperm and eggs at the same time, while sequential hermaphrodites are male during one life phase and female during another. Tilefish are one of the few fish species that exhibit sequential hermaphroditism. Typically, these fish are female when they are young, but become males later in life. The Indo-Pacific cleaner wrasse, Labroides dimidiatus, also changes from female to male later in life. Large males form harems of up to 10 females. Within the females there is a pecking order, determined by size. The largest females get more breeding access to the males. If a female dies, the rest of the females move up in the pecking order. If the male dies, the top female starts to court the females and within two weeks, is transformed into a fully functional male!

13.Frigid females

 

 

Atlantic silversides are unique among fishes as they exhibit temperature dependent sex determination, like most reptiles! The temperature of the environment at the time of metamorphosis (about 50 days after the eggs hatch) determines whether the young are male or female! In colder water, the larvae are most likely to develop into females, while males are typically generated during the warm summer months. Why is this advantageous? Because temperature varies with the season, thedifferent sexes develop at different times of the year. Females, which develop in the cooler temperatures of the early spring, have all summer to grow and thus have a better chance of surviving the cold winter and producing more young in the next spawning season.

14.Sex on the Beach!

Capelin (Mallotus villosus)

 

 

Capelin have decided that spawning in the water is not for them. Each year in June and July they gather by the thousands on coarse sand or fine gravel beaches to spawn. The eggs adhere to sand grains and are buried by wave action to depths up to 15 cm. Buried eggs are safe from wave action and predation. The eggs are laid in abundance: often there are more than 800 eggs in a square centimetre!. After spawning, many fish are often left stranded on the beach; either too tired or too far up on the beach to get reach the water. This observation resulted in the myth that capelin spawn only once. In fact, some do make it back to the water and return again to spawn.

（注明：以上均转载自http://www.aquatic.uoguelph.ca/fish/index.htm，谢谢阅读）