Levels of Tetrodotoxins in Spawning Pufferfish, Takifugu alboplumbeus.

Tetrodotoxin (TTX), also known as pufferfish toxin, is an extremely potent neurotoxin thought to be used as a biological defense compound in organisms bearing it. Although TTX was thought to function as a chemical agent for defense and anti-predation and an attractant for TTX-bearing animals including pufferfish, it has recently been demonstrated that pufferfish were also attracted to 5,6,11-trideoxyTTX, a related compound, rather than TTX alone. In this study, we attempted to estimate the roles of TTXs (TTX and 5,6,11-trideoxyTTX) in the pufferfish, Takifugu alboplumbeus, through examining the location of TTXs in various tissues of spawning pufferfish from Enoshima and Kamogawa, Japan. TTXs levels in the Kamogawa population were higher than those in the Enoshima population, and there was no significant difference in the amount of TTXs between the sexes in either population. Individual differences were greater in females than in males. However, the location of both substances in tissues differed significantly between sexes: male pufferfish accumulated most of their TTX in the skin and liver and most of their 5,6,11-trideoxyTTX in the skin, whereas females accumulated most of their TTX and 5,6,11-trideoxyTTX in the ovaries and skin.

Utilization of Function Generation Synthesis on Biomimetics: A Case Study on Moray Eel Double Jaw Design.

Throughout history, humans have observed living or non-living things in nature and then imitated them in relation to these observations. This is due to the fact that the energy found in nature is generally consumed at an optimal level in order for it to endure. Biomimetic inspiration in many designs and applications is widely displayed, including within the field of engineering. In this paper, we were inspired by the double set of jaws found in the moray eel, which gives this fish a huge advantage while hunting, with a mobile pharyngeal jaw that works together with its oral jaw in order to overcome ineffective suction capabilities. A procedure that mimics the hunting motion of the moray eel was utilized by considering the overall movement as a single degree of freedom with multiple outputs on account of the repeating motion that is required during hunting. This procedure includes structural and dimensioning synthesis, wherein the latter was utilized with analytic kinematic synthesis for each linkage transfer. The flexibilities in parameters were taken into account with a novel multiple iterative kinematic synthesis algorithm that resulted in various mechanisms with the same purpose. Among the excessive number of resultant mechanisms, the optimization was carried out by considering the highest torque transmission ratio at critical timings that were specified as bio-constraints. In the end, the kinematic movement validation was utilized.

Ciguatoxin Detection in Flesh and Liver of Relevant Fish Species from the Canary Islands.

The Canary Islands are a ciguatoxin (CTX) hotspot with an established official monitoring for the detection of CTX in fish flesh from the authorised points of first sale. Fish caught by recreational fishermen are not officially tested and the consumption of toxic viscera or flesh could lead to ciguatera poisoning (CP). The objectives of this study were to determine the presence of CTX-like toxicity in relevant species from this archipelago, compare CTX levels in liver and flesh and examine possible factors involved in their toxicity. Sixty amberjack (Seriola spp.), 27 dusky grouper (Epinephelus marginatus), 11 black moray eels (Muraena helena) and 11 common two-banded seabream (Diplodus vulgaris) were analysed by cell-based assay (CBA) and Caribbean ciguatoxin-1 (C-CTX1) was detected by liquid chromatography mass spectrometry (LC-MS/MS) in all these species. Most of the liver displayed higher CTX levels than flesh and even individuals without detectable CTX in flesh exhibited hepatic toxicity. Black moray eels stand out for the large difference between CTX concentration in both tissues. None of the specimens with non-toxic liver showed toxicity in flesh. This is the first evidence of the presence of C-CTX1 in the common two-banded seabream and the first report of toxicity comparison between liver and muscle from relevant fish species captured in the Canary Islands.

Presence of CTXs in moray eels and dusky groupers in the marine environment of the Canary Islands.

Local population frequently consumes moray eels and dusky groupers from the Canary Islands. These species are top predators and the interactions between them include predation but also, in some cases, collaborative hunting. These fish are well known to cause ciguatera (CFP) outbreaks in several marine areas such as Japan, Hawaii, French Polynesia and Caribe. Groupers have been involved in CFP events in the Canary Islands, however, moray eels have not yet been well studied in this regard. The present research seeks to describe the finding of a black moray in the stomach of a positive dusky grouper during its necropsy, and to clarify the implication of groupers and moray eels in the food webs, accumulating CTXs in the Canarian environment. The study also updates statistics on the presence of toxic groupers in this archipelago. For these purposes, 248 grouper samples from the CFP official control in the Canary Islands (2018-2019) were analysed and 36 moray eels (5 species) were collected under the EuroCigua project and one was obtained during a dusky grouper necropsy. All samples were analysed with the Neuro-2a cell-based assay (CBA) to evidence CTX-like toxicity. Regarding the necropsied grouper and the moray eel found in its stomach content, the LCMS/MS method allowed the identification and quantification of CCTX1 in both fish at similar levels while none of the P-CTXs for which standards were available were detected. Among groupers, 25.4 % displayed CTX-like toxicity with differences between islands. For moray eels 38.9 % showed toxicity, involving 4 species. Black moray exhibited a high proportion of positives (9/12) and a positive correlation was found between CTX-like toxicity quantification and the black moray weight. Regarding the grouper, and the moray eel found in its stomach, the LCMS/MS method allowed the identification and quantification of C-CTX1 in both fish at similar levels. This found suggests a trophic interaction between these species and their role in maintaining CTXs in the Canary waters where local population commonly demand those species for consumption. The island of El Hierro stands out above all the other Canary Islands with the concerning percentage of positive grouper samples and the high CTX toxicity levels obtained in moray eel specimens analysed in this marine area. This is the first report of CTX-like toxicity in flesh of moray eels fished in the Canary archipelago and the confirmation of the presence of C-CTX1 by LCMS/MS in a black moray from this marine area.

Effects of prey characteristics on the feeding behaviors of an apex marine predator, the California moray (Gymnothorax mordax).

Moray eels comprise a large radiation of elongate marine predators that are thought to swallow large prey whole but also circumvent gape constraints by manipulating prey into more manageable pieces. Prey manipulation behaviors include shaking, rotation, knotting, and ramming prey against another object to assist in swallowing. Most morays feed on a wide variety of prey that vary in mechanical properties such as stiffness and toughness, which could potentially affect feeding behaviors. There is little diet data informing us of the maximum prey size morays can swallow whole and whether maximum prey size differs between prey types. Our study examines feeding behaviors for the California moray (Gymnothorax mordax) in the laboratory. We recorded morays feeding on freshly thawed fish and cephalopods of varying size. We found that prey size had a strong effect on total feeding time and manipulation duration for both fish and cephalopods. While morays were observed using a diversity of prey manipulation behaviors and the durations for each of these behaviors increased with prey size, prey type had no effect on manipulation behaviors employed. Total manipulation duration, however, comprised a greater proportion of total feeding time for fish compared to cephalopods. As relative prey mass (RPM) increased for cephalopods, morays spent a greater proportion of their total feeding time transporting prey. Transport rate was higher for cephalopod prey but the relationship between RPM and transport rate was negative for both prey types. Despite this decrease in transport rate, we attribute the lower total feeding times for larger cephalopod prey compared to fish to behavioral tactics of morays. Morays used the corners of the aquaria to aid in the transport of larger cephalopod prey. We hypothesize that the deformable tissues of cephalopods and the presumably low coefficient of friction of their thawed mantles and tentacles may be difficult for the recurved teeth on the pharyngeal jaws to pierce and grip during transport.

Complete mitogenome of two moray eels of Gymnothorax formosus and Scuticaria tigrina (Anguilliformes: Muraenidae).

In this study, the complete mitogenome sequence of two moray eels of Gymnothorax formosus and Scuticaria tigrina (Anguilliformes: Muraenidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome, with the length of 16,558 bp for G. formosus and 16,521 bp for S. tigrina, shows 78% identity to each other. Both mitogenomes follow the typical vertebrate arrangement, including 13 protein coding genes, 22 transfer RNAs, two ribosomal RNAs genes, and a non-coding control region of D-loop. The length of D-loop is 927 bp (G. formosus) and 850 bp (S. tigrina), which is located between tRNA-Pro and tRNA-Phe. The overall GC content is 45.5% for G. formosus and 47.9% for S. tigrina. Complete mitogenomes of G. formosus and S. tigrina provide essential and important DNA molecular data for further phylogenetic and evolutionary analysis for moray eel.

First report on the record of parasitic infection in the Moray eel (Thyrsoidea macrura) along the Parangipettai coastal waters (Southeast coast of India).

An isopod belongs to the family Cirolanidae namely Anopsilana sp. was recorded from Parangipettai coastal waters during February and March, 2011. This is the first report and first record of occurrence of parasite in the Moray eel from this region. In the present study, totally 110 specimens of Moray eel (Thyrsoidea macrura) were examined for parasites and discussed about parasitic infection.