Fish fights

A male in his territory (front) and an intruding male (back)

A male in his territory (front) and an intruding male (back)

The activities are as follows:

In many animals, males fight for territories. Getting a good territory and making sure other males don’t steal it is very important! Males use these territories to attract females for mating. The males that get the best territories are more likely to mate with females and have more babies. Only the males that have babies will pass on their genes to the next generation.

Stickleback fish use the shallow bottom areas of lakes to mate. Male stickleback fish fight each other to gain the best territories in this habitat. In their territories, males build a nest out of sand, aquatic plants, and glue they produce from their kidneys. The better the nest, the more females a male can attract. Males then use courtship dances to attract females to their nests. If a female likes a male, she will deposit her eggs in his nest. Then the male will care for those eggs and protect the offspring that hatch.

Scientist Alycia out in the field collecting male stickleback fish for her experiments

Scientist Alycia out in the field collecting male stickleback fish for her experiments

Alycia is a scientist who is interested in understanding what makes a male stickleback a good fighter and defender of his territory. Perhaps more aggressive males are better at defending their territory and nests because they are better at fighting off other males. She used sticklebacks she collected from British Columbia to test her hypothesis.

In her experiment, 24 males were kept in 6 large tanks, with 4 males in each tank. Alycia watched each of the 24 males every day for 10 days. She recorded the behaviors of each fish when they were competing for territories, defending their territory, and building their nests. She also recorded the size of the males’ territories and whether they had a nest each day.

Featured scientist: Alycia R. Lackey from Michigan State University

Flesch–Kincaid Reading Grade Level = 7.7

More news on Alycia’s work on stickleback fish can be found at her BEACON blog post, “Making and Breaking a Species” and her blog post for the MSU museum

A male (right) defending his territory from another fish (left).

A male (right) defending his territory from another fish (left).

Which guy should she choose?

sticklebackmale

A male stickleback tending his nest. Notice the male’s bright red throat, blue eye, and blue-green body.

The activities are as follows:

In many animals, males use complex behaviors to attract females. They use displays to show off colorful parts of their bodies, like feathers or scales. For example, male peacocks fan out and shake their colorful tails to attract female attention. These displays take up a lot of energy, and yet some males are unable to attract any females while other males attract many females.

In stickleback fish, males are very colorful to attract females. Their throats turn bright red during the spring when they mate. Stickleback males also court females with zig-zag swimming! The males swim in a z-shaped pattern in front of the female, probably to show off their mating colors. Before male fish can get the attention of female fish, they must gain a territory and build a nest. In sticklebacks, females inspect nests that the males build and then decide if they want to deposit their eggs. Males care for the offspring before and after the eggs hatch. A female fish would benefit from identifying “high quality” males and choosing those males for mates. High quality males would have more energy to protect their offspring and would make better fathers. They could also pass on genes that make offspring more attractive to females in the next generation.

Scientist Alycia collecting fish from a freshwater lake in British Columbia, Canada.

Scientist Alycia collecting fish from a freshwater lake in British Columbia, Canada.

Alycia is a scientist who is interested in the stickleback’s mating behaviors. She wanted to figure out why there are differences between males and why certain males can attract a mate while others cannot. What is it about the way a male looks, moves, or smells that attracts females? What male traits are females looking at when deciding on a mate? Alycia thought female sticklebacks may choose males with redder throats and/or more complex behaviors because those traits show the female that those males are high quality. Previous work with these fish showed that male behavior, color, or territory size, or the presence of a nest could all be important. But it was still not clear which characteristic might be most important.

Alycia set up an experiment to figure out if male throat color or zig-zag swimming behaviors were attractive to females. She used a total of 24 male fish and six 75-gallon tanks. She divided the males up evenly between the large tanks, placing four males in each one. For 10 days she observed the male fish and recorded competition behaviors, territory defense, and nest building. On the tenth day, she introduced one female to each tank of four males. She recorded how the males behaved in courtship and which males the females chose. She also recorded the redness of each male.

Featured scientist: Alycia R. Lackey from Michigan State University

Flesch–Kincaid Reading Grade Level = 7.9

More news on Alycia’s work on stickleback fish can be found at her BEACON blog post, “Making and Breaking a Species” and her blog post for the MSU museum

Dangerously bold

An aquarium filled with young bluegill sunfish. Bluegills are a common type of fish that live in freshwater lakes in the eastern United States.

An aquarium filled with young bluegill sunfish. Bluegills are a common type of fish that live in freshwater lakes in the eastern United States.

The activities are as follows:

1

Just as each person has her or his own personality, animals of the same species can behave very differently from one another! For example, pets, like dogs, have different personalities. Some have a lot of energy, some are cuddly, and some like to be alone. Boldness is a recognized behavior that describes whether or not an individual takes risks. Bold individuals take risks while shy individuals do not. The risks animals take have a big impact on their survival and the habitats they choose to search for food.

Bluegill sunfish are a type of fish that lives in freshwater lakes and ponds across the world. Open water and cover are two habitat types where young bluegill are found. The open water habitat in the center of the pond is the best place for bluegill to eat a lot of food. However, the open water is risky and has very few plants or other places to hide. Predators, like large birds, can easily find and eat bluegill in the open water. The cover habitat at the edge of the pond has many plants and places to hide from predators, but it has less food that is best for bluegill to grow fast. Both habitats have costs and benefits—called a tradeoff.

To determine their personality, Melissa observed bluegill sunfish in the aquarium lab.

To determine their personality, Melissa observed bluegill sunfish in the aquarium lab.

Melissa is a scientist who is interested in whether differences in young bluegill behavior changes the habitats in which they choose to search for food. First, she looked at whether young bluegill have different personalities by bringing them into an aquarium lab and watching their behavior. Melissa observed that, just like in humans and dogs, bluegill sunfish have different personalities. She noticed that some bluegill took more risks and were bolder than others. Melissa wanted to know if these differences in behavior could also be observed in her experimental pond. She reasoned that being in open water is risky, but results in more access to food. Therefore, bold fish should take more risks and use the open water habitat more than shy fish, giving them more food, allowing them to grow faster and larger, but exposing them to more predation. Just the opposite should be true about shy fish: more time for them in the cover habitat of the pond exposing them to less predation, but also giving them less access to food and an overall smaller body size than bold fish. A tradeoff for both types of fish based on personality.

Melissa designed a study to test the growth and survival of bold and shy fish. When she was watching the fish’s behavior in the lab, she determined if a fish was bold or shy. If a fish took the risk of leaving the safety of the vegetation in a tank so that it could eat food while there was a predator behind a mesh screen, it was called bold. If it did not eat, it was called shy. She marked each fish by clipping the right fin if it was bold or the left fin if it was shy. She placed 100 bold and 100 shy bluegill into an experimental pond with two largemouth bass (predators). The shy and bold fish started the experiment at similar lengths and weights. After two months, she drained the pond and found every bluegill that survived. She recorded whether each fish that survived was bold or shy and measured their growth (length and weight).

Featured scientist: Melissa Kjelvik from Michigan State University

Flesch–Kincaid Reading Grade Level = 7.3

Photo Jul 23, 5 41 38 PM

A view of the aquarium tank used to determine fish personality. A largemouth bass is placed to the left of the barrier, while 3 bluegill sunfish are placed to the right. If a sunfish swims out of the vegetation and eats a bloodworm dropped near the predator, it is considered bold.

A view of the aquarium tank used to determine fish personality. A largemouth bass is placed to the left of the barrier, while 3 bluegill sunfish are placed to the right. If a sunfish swims out of the vegetation and eats a bloodworm dropped near the predator, it is considered bold.

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