TN00104 JOHNNY DARTER ETHEOSTOMA NIGRUM NIGRUM
Physical description: This species is characterized by narrowly connected brachiostegal membrane *1819*. It has a slender body with posterior compression, short head and blunt snout. The opercle is scaled, and the nape, breast, and belly are partly scaled or unscaled. The maximum length 60 mm. The dorsum is straw-colored or light green with 6 dark brown saddles and spots of light brown. The venter is white, and along the midside is a series of brown W-shaped marks, also present are black pre- and suborbital bars, and a round basicaudal spot. The dorsal caudal and pectoral fins have light bands formed of concentric rows of brown spots along the spines. Other fins are clear or yellow. The male is characterized by a black blotch between the first two spines of the first dorsal fin. The breeding male is darker, especially in the area of the head and fins, with dark vertical bars on the side of the body. The first dorsal fin has a large anterior black spot and the spines may develop terminal white knobs. The breeding female has a large, flat bilobed genital papilla *1819*. The males average length is 49 mm and females average 46 mm *816*. Reproduction: Spawning occurs from April-June with the eggs forming in the late summer and enlarging until spawning takes place. The male is highly territorial defending his rock that he has chosen for nest site and will seldom leave the area. There is no territorial behavior at night, and the female displays no territorial behavior and will move about freely. During spawning, a female will enter a territory and the male will swim upside-down to attract the female. The male then prods the female to stimulate egg laying while the vibrations of the female during laying stimulates the male to release sperm. The male constantly rubs the eggs with his fins until they hatch. During April when water temperatures average 12 degrees C, the eggs will hatch in 16 days. During May when water temperatures reaches 19 degrees C, hatching takes place in about 10 days, and in June the eggs hatch in 6 days in water reaching about 21 degrees C. Fecundity is a function of both age and standard length, and at 1 year a female will lay approximately 90 eggs, and the the following year the same female may lay up to 164 eggs. The female spawns once each season with nearly all mature ova being spawned and 92% of the eggs hatching. The eggs laid after May 15 have a 14% better chance of survival than those laid earlier *2284,2285,1819*. The eggs are laid in a single layer on the underside of a flat rock in slow currents *1124,2138*. The male guards the nest *1124,2138*. Behavior: The territory of the male will radiate out from the opening under the nest rock, while the shape of the area corresponds to the position of the rock. The territory consists of only 2 dimensions *2284,2285*. Origin: This species is native in Virginia *4205*. Population parameters: The maximum age for this species is 4 years with a higher percentage of females surviving to the 4th year *1819*. Aquatic/terrestrial associations: This species is associated with Lampetra hubbsi, L. aepyptera, L. lamottei, Ichthyomyzon sp., Acipenser brevirostrum, Lepisosteus platostomus, Anguilla rostrata, Dorosoma cepedianum, D. petenense, Clupea harengus, Opisthonema oglinum, Salmo qairdneri, Umbra pygmaea, Esox lucius, E. niger, Cyprinus carpio, Ericymba buccata, Exoglossum maxillingua, Hybopsis aestivalis, H. cahni, H. hypsinotus, H. insignis, Nocomis micropogon, N. raneyi and Notropis albeolus *816*. PHYSICAL DESCRIPTION: E. N. SUSANAE IS DIFFERENTIATED FROM E. N. NIGRUM BY AN INTERRUPTED PREORBITAL STRIPE, AN INTERRUPTED PREOPERCULOMANDIBULAR CANAL, AND THE ABSENCE OF SCALES ON TOP OF THE HEAD, ON THE OPERCLE, AND ALONG THE MIDBELLY *TN5017* BEHAVIOR: FOOD IS LOCATED PRIMARILY BY SIGHT, THOUGH ODOR MAY PLAY A MINOR ROLE *TN5071*, THE MALE ESTABLISHES A TERRITORY UNDER A STONE IN A SLUGGISH AREA OF THE STREAM AND CLEANS THE UNDERSIDE OF THE STONE, LATER TO BE USED AS A SITE FOR EGG DEPOSITION, BY MOVING OVER THE STONE WHILE UPSIDE DOWN *TN5017*, JOHNNY DARTERS REACT TO THE SMELL OR PERHAPS TASTE OF SKIN EXTRACTS FROM COMPATRIOTS BY REDUCING THEIR ACTIVITY, A REACTION BELIEVED TO BE AN ALARM REACTION, ARE BELIEVED TO BE DAYTIME BENTHIC FEEDERS AND TO COMPETE MINIMALLY WITH PERCINA MACULATA *TN5018*
| Life History |
References for Life History Codes
835, 1115, 1124, 2138, 816, 2284, 2285, 1819, 4205
Comments on Life History Codes
This species is absent from Atlantic coast streams, and replaced there by the tesselated darter *835,1115*.