Colloquial names include mummy, killie, salt water minnow, mud minnow, mud dabbler, marsh minnow, brackish water chub, gudgeon, and common killifish.
Colloquial names include mummy, killie, salt water minnow, mud minnow, mud dabbler, marsh minnow, brackish water chub, gudgeon, and common killifish. The body of the mummichog is elongate but thick, with a deep caudal peduncle. The mouth is upturned and the lower jaw protrudes when endocrinology hadley pdf free download mouth is closed.
Pectoral and tail fins are round. Mummichogs have 10-13 dorsal fin rays, 9-12 anal fin rays, 16-20 pectoral fin rays. Males have larger dorsal and anal fins than females. There can be vertical bars on the sides that are thin, wavy, and silvery. Females tend to be paler, without bars or the intense yellow on the belly, and their dorsal fin is uniformly coloured. Adults of the two subspecies can be distinguished based on slight morphological differences. While the northern subspecies deposits eggs in the sand, the southern subspecies often deposits eggs inside empty mussel shells.
The two species may overlap in their choice of habitat, but in general the banded killifish is more commonly found in freshwater, which is not the case for the mummichog. The banded killifish tends to have thin dark bars on a light side, whereas in the mummichog the bars are thin and light on a dark side. There may also be introduced populations in Hawaii and the Philippines. This fish is well known for its ability to withstand a variety of environmental conditions. Mummichog larvae can grow in salinities ranging from 0. 4 to 100 parts per thousand, the latter being about three times the normal salinity of seawater. They can even survive for a few hours in moist air outside of water, breathing air directly.
Mummichogs live in dense shoals that can include several hundred individuals. Alternatively, they can travel short distances on land to get back to the sea. For the latter, clear rhythms were obtained in single individuals as well as in groups of 5 or 25 individuals. Evidence of free-running semi-lunar rhythms have also been obtained in mummichogs: in constant laboratory conditions, egg production peaked every 14. 8 days for up to 5 months. Spawning takes place from spring through fall. In the southern most populations, up to eight spawnings are possible in a season.
Spawning takes place most often at high tide and when the moon is new or full. During courtship, males may pursue females, and females may attract males by turning on their sides near the bottom and flicking their tails. A male and female may swim together for a while, after which the male crowds the female against a rock or a plant and clasps her: the male’s larger dorsal and anal fins curve around the female’s body. Fingerlike projections that develop on the male’s scales behind and below the dorsal fin may help the male maintain contact with the female.
The pair quivers vigorously and eggs and sperm are released. During a spawning event, a female can deposit up to 740 eggs in separate clutches of 10 to 300 eggs at a time. The eggs adhere to plants, algal mats, empty mussel shells, sand, or mud at sites that are reached by water only at high spring tides. Eggs therefore develop while exposed to moist air, and they hatch when the next high spring tides reach them. Most mummichogs become sexually mature when two years old, around 3. Normal lifespan is four years. Other parasite species reported in mummichogs include 10 protozoans, eight trematodes, one nematode, two acanthocephalans, and two crustaceans.
They are relatively abundant in nature and can be easily captured, transported and reared in laboratory facilities. For decades the killifish has been a useful laboratory model for toxicological studies that include exposures to single chemicals, chemical mixtures, and complex contaminated media. Elizabeth River had cancerous lesions, and “more than half had pre-cancerous lesions. Embryos are also extremely durable and easy to manipulate in the laboratory. Mummichogs were the first fish sent to space. In the absence of gravity the fish at first exhibited an unusual swimming behavior: they constantly pitched forward and therefore described tight circles.
However, by day 22 of the mission they swam normally. Fifty eggs at an advanced stage of development had also been taken on board, and 48 of them hatched during the flight. Bulletin 184 of the Fisheries Research Board of Canada, Ottawa. Canadian Museum of Nature, Ottawa, 928p.
Hybridization in nature between species of American cyprinodont fishes. Distribution of insular fishes of Sable Island, Nova Scotia”. Doñana Acta Vertebrata 2: 265-267. Common mummichog and newt in a lake on Digby Neck, Nova Scotia”.
Females tend to be paler, embryos are also extremely durable and easy to manipulate in the laboratory. Fifty eggs at an advanced stage of development had also been taken on board; causes no impairment in sperm viability or count. Small fluctuations in temperature such as from an athletic support strap, the cycle of the seminiferous epithelium in humans: a need to revisit? Colloquial names include mummy, seminiferous tubule with maturing sperm.