Swimming direction of the glass catfish is responsive to magnetic stimulation

Several marine species have developed a magnetic perception that is essential for navigation and detection of prey and predators. One of these species is the transparent glass catfish that contains an ampullary organ dedicated to sense magnetic fields. Here we examine the behavior of the glass catfish in response to static magnetic fields which will provide valuable insight on function of this magnetic response. By utilizing state of the art animal tracking software and artificial intelligence approaches, we quantified the effects of magnetic fields on the swimming direction of glass catfish. The results demonstrate that glass catfish placed in a radial arm maze, consistently swim away from magnetic fields over 20 μT and show adaptability to changing magnetic field direction and location.

Swimming direction of the glass catfish is responsive to magnetic stimulation

Several marine species have developed a magnetic perception that is essential for navigation and detection of prey and predators. One of these species is the transparent glass catfish that contains an ampullary organ dedicated to sense magnetic fields. Here we examine the behavior of the glass catfish in response to static magnetic fields which will provide valuable insight on function of this magnetic response. By utilizing state of the art animal tracking software and artificial intelligence approaches, we quantified the effects of magnetic fields on the swimming direction of glass catfish. The results demonstrate that glass catfish placed in a radial arm maze, consistently swim away from magnetic fields over 20 µT and show adaptability to changing magnetic field direction and location.

Insights into electrosensory organ development, physiology and evolution from a lateral line-enriched transcriptome

The anamniote lateral line system, comprising mechanosensory neuromasts and electrosensory ampullary organs, is a useful model for investigating the developmental and evolutionary diversification of different organs and cell types. Zebrafish neuromast development is increasingly well understood, but neither zebrafish nor Xenopus is electroreceptive and our molecular understanding of ampullary organ development is rudimentary. We have used RNA-seq to generate a lateral line-enriched gene-set from late-larval paddlefish (Polyodon spathula). Validation of a subset reveals expression in developing ampullary organs of transcription factor genes critical for hair cell development, and genes essential for glutamate release at hair cell ribbon synapses, suggesting close developmental, physiological and evolutionary links between non-teleost electroreceptors and hair cells. We identify an ampullary organ-specific proneural transcription factor, and candidates for the voltage-sensing L-type Cav channel and rectifying Kv channel predicted from skate (cartilaginous fish) ampullary organ electrophysiology. Overall, our results illuminate ampullary organ development, physiology and evolution.

On the Development of Electroreceptive Ampullary Organs of Triturus alpestris (Amphibia: Urodela)

The ontogenesis of the organs of the lateral-line system of the alpine newt (Triturus alpestris) was examined with special emphasis on the ampullary organs using resin embedded thick sections. The mechanoreceptive neuromasts and the electroreceptive ampullary organ were indistinguishable prior to hatching. At hatching only few ampullary organs were found around the eye. These organs consist of one or two egg-shaped sensory cells and a few supporting cells. The ratio of ampullary organs and neuromasts changes from 1:15.6 (stage 36) to 1:1.1 (stage 62). The number of unidentifiable organs decreases constantly over this period of time and becomes zero at the oldest stages observed. Besides an absolute numerical increase in both types of organs both grow by increasing the number of cells per organ. Comparison with the development of the ampullary organs in catfish shows a striking similarity which suggest either similar functional constraints acting on both catfish and newts or can be interpreted as an indication of homology of both types of organs.