Stickleback

The stickleback is a small fish.

It lives in the sea and in lakes. These fish eat tiny bugs and small sea life. Some have hard plates on their bodies. Others have sharp spines on their backs.

In fresh water, the dads turn bright red. They build nests using weeds. The dad stays to guard the eggs until they hatch.

Some fish are bold. Other fish are shy. They are very busy fish!

Sticklebacks are a family of small fish. They live in oceans and lakes. Most live in salt water. Some live in fresh water.

These fish eat small animals. They eat insects and tiny shrimp. Most sticklebacks are small. The three-spined stickleback is about 4 inches long. One other kind is much larger. The fifteen-spined stickleback can reach 8.8 inches.

Sticklebacks have unique bodies. They have sharp spines on their backs. Most have no scales. Some have bony plates instead.

Male fish have a special way of making babies. In fresh water, the dads turn bright red. They build nests from weeds. They use a special glue from their bodies. The male guards the eggs until they hatch. This can take 7 to 14 days.

Both moms and dads choose their mates. Females like males with bright red throats. Males like females that are large. Large females often have bigger eggs. This helps the babies survive. Some fish are bold. Other fish are shy.

Sticklebacks are a family of small fishes called Gasterosteidae. They live in many places around the world. You can find them in oceans, lakes, and even brackish water. Some live in the salty sea. Others live in fresh water like rivers or ponds. Many freshwater fish were trapped in places like Europe and North America after the Ice Age ended. This happened about 10,000 to 20,000 years ago.

These fishes have very interesting bodies. Most sticklebacks are quite small. The three-spined stickleback usually grows to about 3 inches long. However, the fifteen-spined stickleback is much larger. It can reach about 8.8 inches in length. Sticklebacks are carnivores, which means they eat meat. They hunt for small animals like insects and tiny shrimp. They also eat fish larvae. They have strong spines on their backs to stay safe.

Scientists have studied these fishes for a long time. A French zoologist named Charles Lucien Bonaparte named the family in 1831. Later, a scientist named Niko Tinbergen studied how they act. His work helped start a field called ethology. Ethology is the study of how animals behave. Today, sticklebacks are like a "supermodel" for science. This means they are perfect for studying how genes and nature work together. In 2012, scientists even mapped their whole genome.

Making babies is a big job for a stickleback. In fresh water, the males turn bright red. The male builds a nest using weeds. He uses a special glue called spiggin from his kidneys. The female lays her eggs in the nest. Then, the male fertilizes them and guards them. He stays with the eggs for 7 to 14 days. This helps the eggs hatch safely. Some males even guard the tiny babies after they hatch.

Both moms and dads are very picky about their mates. Females like males with bright red throats. This color might show that the male is healthy. Males like females that are large or have big bellies. Larger females usually have bigger eggs. Big eggs help the babies grow strong. Sticklebacks also try to avoid inbreeding. This means they choose mates that are not their relatives. Choosing a new mate helps the babies survive better.

Sticklebacks belong to a family of ray-finned fishes called Gasterosteidae. These fish live in many different environments across the Holarctic region. You can find them in the ocean, in fresh water, or in brackish water. Brackish water is a mix of fresh and salty water. Most sticklebacks live in the ocean, but some live in lakes and rivers. Many freshwater groups were trapped in Europe, Asia, and North America after the Ice Age ended. This happened between 10,000 and 20,000 years ago.

Sticklebacks have unique physical features that help them survive. They are characterized by strong, isolated spines in their dorsal fins. These are the fins located on the top of their bodies. Unlike many other fish, most sticklebacks have no scales. However, some species have developed bony armour plates instead. They are carnivorous, meaning they eat other animals. Their diet includes insects, crustaceans, and fish larvae. Their body shape often changes based on where they live. Sticklebacks in shallow lakes often have deep bodies to feed on benthic invertebrates. These are animals that live on the bottom of the water. In contrast, sticklebacks in deep, oligotrophic lakes have slimmer bodies to feed on plankton.

Most sticklebacks are quite small in size. The three-spined stickleback, or Gasterosteus aculeatus, is a well-known species. It usually reaches about 3 inches in length, though its maximum size is about 4 inches. These fish reach sexual maturity when they are about 2 inches long. Most other species are similar in size or even smaller. There is one major exception to this rule. The fifteen-spined stickleback, known as Spinachia spinachia, is much larger. It can grow to reach 22 cm, which is about 8.8 inches.

The history of stickleback science involves many important discoveries. The French zoologist Charles Lucien Bonaparte first proposed the family Gasterosteidae in 1831. For a long time, scientists thought sticklebacks were closely related to seahorses and pipefish. Recent phylogenetic work, which studies evolutionary relationships, has changed this view. We now know they are more closely related to eelpouts and sculpins. Later, the scientist Niko Tinbergen studied their behavior. His work was vital to the early development of ethology, which is the study of animal behavior. He used sticklebacks to demonstrate a fixed action pattern.

Sticklebacks have very complex mating behaviors and rituals. In freshwater, males often develop a bright red color on their throats. The male builds a nest using weeds. He holds these weeds together using a secretion called spiggin. Spiggin is a substance produced by the male's kidneys. After building the nest, the male attracts a female. The courtship often involves a zig-zag dance. During this dance, the male moves in an erratic side-to-side pattern near the female. The female then lays her eggs inside the nest. The male fertilizes them and guards them for 7 to 14 days. This duration depends on the water temperature.

Both males and females show strong preferences when choosing mates. This is known as mutual mate choice. Females often prefer males with bright red coloration. This preference may be linked to the Hamilton-Zuk hypothesis. This idea suggests that red color shows a male is free of parasites. However, some scientists think red color might be a faulty signal. Using carotenoids to make red colors might leave less for the male's germline cells. This could lead to higher oxidative DNA damage and lower sperm quality. On the other hand, males also choose their mates carefully. They often prefer females that are larger and longer. Larger females generally produce larger eggs, which helps offspring survival.

Sticklebacks are also important for modern genetic research. Scientists call them a "supermodel" for studying evolution. This is because they allow researchers to combine many different types of studies. You can look at molecular, developmental, population genetic, and ecological levels all at once. In 2012, researchers described the nearly complete genome sequence of a freshwater stickleback. They also found genetic variants common in 21 different marine and freshwater populations. These variants help scientists understand how fish adapt to different environments. This makes them ideal for studying parallel evolution.