Stickleback

Stickleback
Scientific Classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Actinopterygii Order: Gasterosteiformes Family: Gasterosteidae
Genera
Apeltes Culaea Gasterosteus Pungitius Spinachia
The Stickleback, common among the Faroe islands of Denmark, has made it onto a stamp sold in the region

Sticklebacks are any of the species of freshwater fish belonging to the taxonomic family Family Gasterosteidae. They have enjoyed great success spreading its kind around the world, and can be found in Asia, Europe, and North America. Although a relatively unassuming creature, the stickleback has recently entered the spotlight of the evolutionary debate, as a result of its fantastic ability to rapidly adapt its bone structure to what is required by its environment. The study of natural selection at work on this creature has caused some very controversial claims. However, this hardy species' ability to adapt has contributed greatly to its rapid spread across the globe, having even been found in wells after having gained access through subterranean passages! This creature's ability to adapt is astounding to study and a true example of the wonder of God's creation.

Body Design

The stickleback bears some very interesting characteristics

Sticklebacks, also known as tube snouts, are one of the most plentiful fish in the ocean, and are more closely related to pipefish and seahorses than your average fish.

Though small, the stickleback is easily recognized by its stiff and isolated spines in the dorsal fin. Amazingly, they have no scales, though some sport bony armor plates. One has to look fairly closely, however, as they can only reach about 4 inches, and only a few of them are more than 3 inches long. They mature sexually at a length of about 2 inches. They have several characteristics unusual for fish species, such as all stickleback species have a similar breeding behavior: The males create a nest from flora using secretions from their kidneys. Once finished, the male will wait for a female to come along, who will lay her eggs in the nest. The male will then fertilize the eggs, protecting them until they hatch. Sticklebacks eat small crustaceans and fish. There are only five genera of the stickleback, each with their own unique characteristics:

The Brook Stickleback (Culaea): Grows to about two inches long. They are usually olive green with some pale mottling on the sides, but when males are breeding they turn black. The single dorsal fin (on top) and the anal fin (on the bottom) grow fairly far back on the body, close to the tail, and are triangular. Further separating their appearance from that of the similarly sized minnows, Brook Sticklebacks do not have a forked tail, of course, other than the row of tiny spines on the back in front of the dorsal fin. There are a couple of small pelvic spines as well, but some populations lack these.

The Three Spined Stickleback (Gasterosteus): This particular species is very lean, with a squarish tail fin. It is similar to the Nine-Spined Stickleback, though it is more thickset and looks like it is compressed sideways. Though it is known as the Three Spined Stickleback, specimens can be found with four or five spines. This stickleback’s color scheme encompasses quite a variety of colors, but they are usually deep grayish, or olive-green. They have the potential to reach 5 inches, but most of them are about 4 inches long. They develop sexually at a length of about 3 inches.

The Four Spined Stickleback (Apeltes): The Four Spined Stickleback has quite a different appearance from that of other sticklebacks, with a bony ridge on each side of the abdomen, making it triangular in a cross section. They also have flat belly and sharp back. If one observes it from they side, Four Spined Stickleback looks spindle-shaped, tapering to the rather pointed nose. It has two to four free dorsal spines standing close one behind the other, which point alternately to the left or right, with another spine attached to the dorsal fin by the fin membrane. There is also another, strongly saw-edged, spine right before the anal fin, and each ventral fin. The Four Spined Stickleback is brownish olive or greenish brown, with dark mottlings. The fin membrane of the ventral fins is colored red. Males of this species are easily identified, as they are much darker than females. They can grow to become one and a half to two and a half inches long.

The Nine Spined stickleback (Pungitius): The Nine Spined Stickleback is very small, only growing to a length of 6 centimeters. Its appearance is much like that of other sticklebacks, with a well ridge on the sides, and a fan-like tail fin, though it does have a shallow fork. As with the Three Spined Stickleback, this species does not always have the exact amount of spines its name suggests. One can easily be found with eight to eleven spines on its back. This species also has small bony plates near the front of its body, at the base of its dorsal and anal fins, and also on its belly between the pelvic fins. Adults may range in color from pale green to dark grey, with darker bars or blotches on the sides and a silvery belly.

The Fifteen Spined Stickleback (Spinachia): this species, unlike other sticklebacks, is wholly marine. Also, it does not always have fifteen spines, as it can range from fourteen to sixteen on its back, with an extra 2 pelvic spines and a single anal spine. The Fifteen Spined Stickleback’s dorsal and anal fins are set fairly back along the body close, causing the body shape to look eel-like.It has a long and tubular head and a brown stripe runs through the eye. It is a mottled dark brown along the upper part of the body, and can be light brown to white below.

Life Cycle

A drawing of a male stickleback's nest.

A baby stickleback, known as a fry, spends eight days incubating in a nest guarded incessantly by the male. The male guards his nest, fiercely, which is built from seaweed, pebbles, and other debris, and held together by a special secretion from the male stickleback’s kidney, known as spiggin. After the fry finally hatches, it spends a few days inside the nest, and continues to remain under the protection of its father until it reaches about an inch in length. Once independent, it and several hundred other fry will gather into their own school for mutual protection.

Once our baby stickleback matures into a strapping adult, it will return to the ocean if able and will feed on plankton and algae. If it happens to be one of a freshwater variety, it will feed upon pond vegetation. As they are easy prey for larger fish and birds, they breed quickly, usually living only long enough for one breeding season, although several freshwater types may live from one to two years.

As the stickleback reaches sexual maturity it will traverse to a suitable breeding ground, where the males will stake out territories. The male will also then begin to develop a red coloration and its irises will then turn blue. This coloration signifies to females the quality of the male, as the coloration is not synthesized but generated as a result of the fishes diet. Therefore the female can determine the physical ability of the male by the intensity of its coloration. If a female is successfully wooed by a male, she will lay her eggs in his nest, and will then leave, entrusting the care of the young entirely to the male, and so the cycle begins again.

Ecology

An example of the great diversity of the Stickleback family, this fifteen-spine stickleback is significantly different that its cousins pictured above.

The stickleback has proven to be extremely apt in adapting to its environment, and as such its ecology changes with every single species. Because of this ability, it is extremely widespread and can be found almost everywhere in Europe, Asia, and North America, and is the most commonly found fish in the ocean. However despite the large distribution of this family, there are so many different species being constantly discovered, sometimes a different species in each lake of an area, that there is great difficulty in classifying the environmental status of this animal.

Another reason contributing towards the success of the stickleback is its cognitive (of or pertaining to the mental processes of perception, memory, judgment, and reasoning, as contrasted with emotional and volitional processes. ) intelligence. They have proven adept at learning from the mistakes of their brethren, and at discovering ways of gathering food. In fact in some areas they occur in such great numbers that they are used to create animal feed, fertilizer, and even oil. Also in the Black Sea region they are considered a pest because of their tendency to consume the young of fish who are eaten by humans and also competes with more edible fish for food. Overall, however, they are not considered much of a pest and tend not to bother.

In the UK they are known as the tiddler or sprick, and in the Republic of Ireland they are called pinkeens because of the reddish color of the male three spined stickleback during breeding season. Also due to their extreme ability to adapt and their plethora of different species, they have become a favorite test case in the study of natural selection.

Evolution

In recent years the study of the Stickleback and its extreme variants have caused quite a stir in both Creationist and Evolutionist communities. It has been named a “superstar of evolutionary science” and there has been suggestion that they may very well become the new "Darwin's Finches" The stickleback’s great ability to adapt has been said to “debunk creationists’ claims that evolutionary forces are too wimpy to produce major biological transformations.” However is the Stickleback’s adept abilities at adapting to its environment really evidence of major evolution, capable of turning fish into men?

Evolution, though hard to define, is a process that results in heritable changes in a population spread over many generations. However, for evolution to create whole new creatures new features of that creature must be created. However, the ‘evolution’ of the stickleback has not resulted in any new features, but rather “the reduction or even complete loss complete loss of existing features—bony plates and pelvic spines.” Therefore the stickleback has been experiencing “strong natural selection acting on variation that was carried by the anadromous (Migrating from salt water to spawn in fresh water, as salmon of the genera )fish that colonized the lake.” However many scientists may argue that examples of natural selection prove the broad claims of the theory of evolution, but there are some key differences. Natural selection cannot increase genetic information or act as an originator, but it therefore cannot generate an evolutionary tree of life. Natural selection helps organism adapt to specific environment, as only create variations of the same kind of animal.

Is the stickleback evidence for the evolution of fish into men? Scientists have narrowed the cause of the variation of the stickleback’s bone structure to a mutation in the gene Pitx1, however this is certainly not evidence for the creation of new creatures entirely, as the mutation simply prevents the expression of this gene, causing a change in the bone makeup of the fish. Therefore this change is more accurately described as devolution, defined by leading evolutionary proponent Jerry Coyne as “represent[ing] the loss of traits, rather than the origin of evolutionary novelties.” Therefore despite claims to the contrary, the natural selection in sticklebacks observed by scientists provides no evidence towards the creation of new features in animals, and as such provides no proof towards the theory of evolution.

Gallery

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  Smallhead stickleback
  (Gasterosteus microcephalus)

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  Nine-spined stickleback
  (Pungitius pungitius)

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  Three-spined Stickleback
  (Gasterosteus aculeatus)

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  sakhalin stickleback
  (Pungitius tymensis)