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James Lewis
James Lewis

Catfish (2010)

Where did the name Catfish come from? The name was coined by the father of one of the women that Nev was building an online relationship with on Facebook; Vince. Essentially it is an analogy of cod fishing in Asia and North America whereby fishermen put catfish in the cod tanks as they are being transported long distances to keep them occupied. This relates to how people keep active in their everyday lives in this film, or rather they should most certainly keep an active mind while exploring the internet. This is important to the plot of Catfish since it becomes obvious that when people are given the opportunity to lie, more often than not they do.

Catfish (2010)

Even bigger fish lurk in Lake Fork, and all of them have whiskers. Rod-and-reel anglers have landed blue catfish weighing 71.5 pounds, channel cats weighing 17.73 pounds and flathead catfish tipping the scale at 75 pounds. From Lake Fork, the Bass Capital of the World.

For centuries, a catfish was merely a type of fish with a distinctive face. Then, in 2010, Ariel Schulman released Catfish, a documentary about his brother Nev's experiences with a woman who pretended to be someone else online. (The movie was popular enough to spawn a television show by the same title.) In the documentary, the woman's husband explained the title with an anecdote about how fishermen transporting live cod used to put catfish in with the cod on long-haul shipments to keep the desirable cod active and alert until arrival. The man implied that his wife was like those catfish, keeping the lives of others fresh and interesting.

The oocytes of the freshwater catfish Heteropneustes fossilis hydrate during hormone-induced meiotic maturation. To investigate if this process may be mediated by aquaporins (AQPs), as it occurs in marine fish producing highly hydrated eggs, the cloning of ovarian AQPs in catfish was carried out. Using degenerate primers for conserved domains of the major intrinsic protein (MIP) family, and 5' and 3'end amplification procedures, a full-length cDNA encoding for an AQP1-like protein was isolated. The predicted protein showed the typical six transmembrane domains and two Asn-Pro-Ala (NPA) motifs conserved among the members of the AQP superfamily. Phylogenetic analysis indicated that the catfish AQP clustered with the teleost-specific aquaporin-1b subfamily, and accordingly it was termed HfAqp1b. Heterologous expression in Xenopus laevis oocytes indicated that HfAqp1b encoded for a functional AQP, water permeability being enhanced by cAMP. Site-directed mutagenesis revealed that cAMP induced the translocation of HfAqp1b into the oocyte plasma membrane most likely through the phosphorylation of HfAqp1b Ser(227). In adult catfish, hfaqp1b transcripts were detected exclusively in ovary and brain and showed significant seasonal variations; in the ovary, hfaqp1b was maximally expressed during the pre-spawning period, whereas in the brain the highest expression was detected during spawning. In vitro stimulation of isolated catfish ovarian follicles with vasotocin (VT) or human chorionic gonadotropin (hCG), which induce oocyte maturation and hydration, elevated the hfaqp1b transcript levels after 6 or 16 h of incubation, respectively. These results suggest that HfAqp1b may play a role during VT- and hCG-induced oocyte hydration in catfish, and that VT may regulate HfAqp1b at the transcriptional and post-translational level in a manner similar to the vasopressin-dependent mammalian AQP2.

The rule has yet to be implemented. The proposed rule has languished in the Office of Management and Budget reportedly because of objections raised by the Office of the U.S. Trade Representative over concerns that countries currently exporting catfish to the U.S. may not be able to meet the food safety standards that FSIS would require.

Surveys of ontogenetic development of hearing and sound production in fish are scarce, and the ontogenetic development of acoustic communication has been investigated in only two fish species so far. Studies on the labyrinth fish Trichopsis vittata and the toadfish Halobatrachus didactylus show that the ability to detect conspecific sounds develops during growth. In otophysine fish, which are characterized by Weberian ossicles and improved hearing sensitivities, the ontogenetic development of sound communication has never been investigated. We analysed the ontogeny of the auditory sensitivity and vocalizations in the mochokid catfish Synodontis schoutedeni. Mochokid catfishes of the genus Synodontis are commonly called squeakers because they produce broadband stridulation sounds during abduction and adduction of pectoral fin spines. Fish from six different size groups - from 22 mm standard length to 126 mm - were studied. Hearing thresholds were measured between 50 Hz and 6 kHz using the auditory evoked potentials recording technique; stridulation sounds were recorded and their sound pressure levels determined. Finally, absolute sound power spectra were compared to auditory sensitivity curves within each size group.

This study on the squeaker catfish S. schoutedeni is the first to demonstrate that absolute hearing sensitivity changes during ontogeny in an otophysine fish. This contrasts with prior studies on two cypriniform fish species in which no such change could be observed. Furthermore, S. schoutedeni can detect conspecific sounds at all stages of development, again contrasting with prior findings in fishes.

Fish possess a large diversity in hearing sensitivities. Several non-related groups of bony fish - often termed hearing specialists [1] - have evolved mechanisms which transmit vibrations of air-filled cavities to the inner ear. These mechanisms enable them to detect the pressure component of sound, enhance their absolute hearing sensitivity and broaden the range of detectable frequencies up to several kilohertz [2] versus several hundred Hertz in species without such specialization. Otophysi, a group of mainly freshwater fishes comprising the orders Siluriformes (catfishes), Cypriniformes (carps and loaches), Characiformes (tetras) and Gymnotiformes (South American knifefishes) are characterized by possessing such an accessory auditory structure, the Weberian apparatus. The Weberian apparatus consists of a chain of one to four ossicles that transmit oscillations of the swimbladder in the sound field directly to the inner ear. Catfishes, numbering more than 3,000 known species [3], show a high diversity in the structure of the Weberian apparatus and swimbladders. Their hearing ability depends on swimbladder size as well as on the number of Weberian ossicles [4].

The present study is the first to investigate the ontogenetic development of hearing and sound production in an otophysine fish. The mochokid catfish Synodontis schoutedeni David 1936 emits stridulatory sounds in distress situations and during agonistic interactions by rubbing the spines of its pectoral fins in grooves of the shoulder girdle [27]. Therefore, mochokids are frequently called squeakers. S. schoutedeni shows a well-developed unpaired swimbladder, three Weberian ossicles and very good hearing sensitivities as compared to other species of catfish with a different swimbladder morphology [4]. We describe the developmental changes of temporal, spectral and intensity characteristics of stridulation sounds, analyse the development of auditory sensitivity with growth, and examine whether S. schoutedeni is able to communicate acoustically throughout its life history.

Changes in hearing abilities have been reported in several fish taxa [15, 16, 18, 19]. The present study provides the first evidence that auditory thresholds change during ontogeny in an otophysine fish species (Figure 2), results that are in contrast with previous studies on two species of cypriniforms, namely the goldfish [11] and the zebrafish [14]. Several potential explanations can be forwarded for this discrepancy among otophysines. First, different species have been investigated, which even belong to different orders, namely Cypriniformes and Siluriformes. Furthermore, the authors of those studies did not calculate regressions of hearing abilities including all data from each individual study specimen, but instead compared the mean results of different size groups. Furthermore, the size differences of the goldfish used as well as the range of frequencies tested might have been too small: the specimens were 45 to 48 mm SL and 110 to 120 mm SL, and the five test frequencies ranged from 100 to 2,000 Hz. However, goldfish are able to detect sounds at least up to 4 kHz [28]. In contrast to the goldfish study, Higgs et al. measured early stages of zebrafish (10 mm) [14] and found an extension of the maximum frequency detectable from a 200 Hz upper limit in small specimens up to 4 kHz in large ones but no change in absolute thresholds. They argued that the development of the Weberian ossicles is responsible for this increase in the detectable frequency range. By contrast, Zeddies and Fay [12] found in their study on the development of startle response in zebrafish no change of stimulus thresholds and frequency bandwidth to which the zebrafish responded from five days post fertilization to adult. Similar to the observations of Zeddies and Fay [12] in zebrafish, we did not observe a change in the range of detectable frequencies. Based on Coburn and Grubach's [29] study on the ontogeny of the Weberian ossicles in several species of catfish we assume that all our tested animals possessed fully developed Weberian ossicles. Thus, the current study is the first to systematically demonstrate that auditory thresholds change with size in an otophysine fish (Figure 2), whereas the detectable frequency range does not change (Figures 1 and 2). Auditory sensitivity increased at lower frequencies up to 2 kHz and decreased at 5 and 6 kHz.

These data indicate that smaller individuals within a given species of catfish may hear better at higher frequencies. One possible reason could be that smaller specimens produce sounds of higher frequencies and are adapted to detect sounds of similar-sized conspecifics. Ladich and Yan [33] argued that the pygmy gourami, the smallest species investigated in their comparative study on labyrinth fishes (family Osphronemidae), heard better at 3 to 5 kHz than the larger two species. The authors argued that higher sensitivity at higher frequencies in the smallest species may reflect the higher resonance frequencies of their smaller-sized accessory hearing structures, the so-called suprabranchial chambers (paired air-filled chambers close to the inner ears). 041b061a72


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