Where do fish go when stranded on land? Terrestrial orientation of the mangrove rivulus Kryptolebias marmoratus.

The goal of the present study was to determine which sensory cues the mangrove rivulus Kryptolebias marmoratus, a quasi-amphibious, hermaphroditic fish, uses to orient in an unfamiliar terrestrial environment. In a laboratory setting, K. marmoratus were placed on a terrestrial test arena and were provided the opportunity to move toward reflective surfaces, water, dark colours v.

By land or by sea: a modified C-start motor pattern drives the terrestrial tail-flip.

Aquatic C-start escape responses in teleost fishes are driven by a well-studied network of reticulospinal neurons that produce a motor pattern of simultaneous contraction of axial muscle on the side of the body opposite the threatening stimulus, bending the fish into the characteristic C shape, followed by a traveling wave of muscle contraction on the contralateral side that moves the fish away from the threat. Superficially, the kinematics of the terrestrial tail-flip resemble the C-start, with the anterior body rolling up and over the tail into a tight C shape, followed by straightening as the fish launches off of the caudal peduncle into ballistic flight. We asked whether similar motor control is used for both behaviors in the amphibious mangrove rivulus, Kryptolebias marmoratus Fine-wire bipolar electrodes were percutaneously inserted into repeatable paired axial locations in five individual fish.

Genetic Subdivision and Variation in Selfing Rates Among Central American Populations of the Mangrove Rivulus, Kryptolebias marmoratus.

We used 32 polymorphic microsatellite loci to investigate how a mixed-mating system affects population genetic structure in Central American populations (N = 243 individuals) of the killifish Kryptolebias marmoratus (mangrove rivulus), 1 of 2 of the world's only known self-fertilizing vertebrates. Results were also compared with previous microsatellite surveys of Floridian populations of this species. For several populations in Belize and Honduras, population structure and genetic differentiation were pronounced and higher than in Florida, even though the opposite trend was expected because populations in the latter region were presumably smaller and highly selfing.

Jumping sans legs: does elastic energy storage by the vertebral column power terrestrial jumps in bony fishes?

Despite having no obvious anatomical modifications to facilitate movement over land, numerous small fishes from divergent teleost lineages make brief, voluntary terrestrial forays to escape poor aquatic conditions or to pursue terrestrial prey. Once stranded, these fishes produce a coordinated and effective "tail-flip" jumping behavior, wherein lateral flexion of the axial body into a C-shape, followed by contralateral flexion of the body axis, propels the fish into a ballistic flight-path that covers a distance of multiple body lengths. We ask: how do anatomical structures that evolved in one habitat generate effective movement in a novel habitat? Within this context, we hypothesized that the mechanical properties of the axial skeleton play a critical role in producing effective overland movement, and that tail-flip jumping species demonstrate enhanced elastic energy storage through increased body flexural stiffness or increased body curvature, relative to non-jumping species.

Launches, squiggles and pounces, oh my! The water-land transition in mangrove rivulus (Kryptolebias marmoratus).

Mangrove rivulus (Kryptolebias marmoratus) are small fusiform teleosts (Cyprinodontiformes) with the ability to locomote on land, despite lacking apparent morphological adaptations for terrestrial movement. Rivulus will leave their aquatic habitat for moist, terrestrial environments when water conditions are poor, or, as we show here, to capture terrestrial insects. Specimens were conditioned to eat pinhead crickets on one side of their aquaria.