Mummichog
The mummichog (Fundulus heteroclitus) is a type of killifish. They are more commonly called “mummies” or “gudgeons”. The mummichog gets its name from its tendency to travel in schools; in the Indigenous language of the Narragansett tribe, “mummichog” means “going into crowds”.
Physical Description
Most mummichogs will only grow seven to nine centimeters in length, so they are generally quite small, and they will not grow past a maximum length of 15 cm. The females tend to be larger than the males. Different populations will have their own colouring based on their surroundings and habitat, but the colour of the mummichog is usually between olive green and brown. Males will become darker during the reproductive season, with an orange/yellow underside. Females are generally paler than the males, and develop a shiny underside used to attract a mate during the reproductive season.
Habitat and Diet
Mummichogs are found along the east coast of North America; they prefer brackish water (a mixture of salt and freshwater). However, they can also survive in either salt or freshwater. Because of this wide tolerance of water salinity, they can be found in rivers, estuaries and tidal marshes, often hiding in the muddy floor of the body of water. Mummichogs are one of the toughest fish species because they can withstand water temperatures ranging from six to 35 degrees Celsius, they can grow in waters with high salinity levels, and they can tolerate extremely low levels of oxygen in water. Due to their small size, the habitat of the mummichog is typically a protected or sheltered area close to the shoreline. As omnivores, the mummichogs can eat anything from algae and molluscs to insects.
Life Cycle
The reproductive season for mummichogs is from late spring to early fall, and during that period, a female can reproduce eight times and she can release 430 eggs each time! The best time for a mummichog to reproduce is during a spring tide (which occurs every new moon and full moon) because this is when the tides are the highest. The female attracts the male by shining her reflective underside and then will lay the eggs for external fertilization. The zygotes stick to algae, eelgrass, mud rocks and dead mollusc shells. As the water recedes, and the eggs are exposed to the air, they begin growing. In order to hatch, the eggs have to be covered again by high tide waters. This process is regulated by exposure to oxygen around the eggs from the water or air. Once in the water as juveniles, the mummichogs will continue to grow for 2 years before they finally reach sexual maturity. The average lifespan for a mummichog is 3 years.
Mummichogs and Humans
Humans have many uses for mummichogs, both in science and in daily life. They are often used as a type of fish bait. Also, in the scientific community they are extensively studied in toxicological, physiological and embryological studies. This is because of mummichogs’ high habitat variability and versatility. In fact, mummichogs were used in an experiment in 1973 in which they were sent into space so researchers could study movement patterns in zero gravity and weightlessness conditions.
Back on earth, mummichogs are also used to control mosquito populations. Mosquitoes will often lay their eggs in shallow pools of water, which is the exact habitat of these fish. A mummichog is able to eat up to 2000 mosquito larvae a day, acting as a control on the mosquito population.
Ryan Small
