Developmental Evolution of Hypaxial Muscles: Insights From Cyclostomes and Chondrichthyans

Jawed vertebrates possess two distinct groups of muscles in the trunk (epaxial and hypaxial muscles) primarily defined by the pattern of motor innervation from the spinal cord. Of these, the hypaxial group includes muscles with highly differentiated morphology and function, such as the muscles associated with paired limbs, shoulder girdles and tongue/infrahyoid (hypobranchial) muscles. Here we summarize the latest findings on the evolutionary mechanisms underlying the morphological variety of hypaxial musculature, with special reference to the molecular insights obtained from several living species that diverged early in vertebrate evolution. Lampreys, extant jawless vertebrates, lack many of derived traits characteristic of the gnathostomes, such as jaws, paired fins and epaxial/hypaxial distinction of the trunk skeletal musculatures. However, these animals possess the primitive form of the hypobranchial muscle. Of the gnathostomes, the elasmobranchs exhibit developmental mode of hypaxial muscles that is not identical to that of other gnathostomes in that the muscle primordia relocate as coherent cell aggregates. Comparison of expression of developmental genes, including Lbx genes, has delineated the temporal order of differentiation of various skeletal muscles, such as the hypobranchial, posterior pharyngeal and cucullaris (trapezius) muscles. We have proposed that the sequential addition of distal muscles, associated with expression of duplicated Lbx genes, promoted the elaboration of skeletal musculature. These analyses have revealed the framework of an evolutionary pathway that gave rise to the morphological complexity and diversity of vertebrate body patterns.

Capturing and analyzing pattern diversity: an example using the melanistic spotted patterns of leopard geckos

Animal color patterns are widely studied in ecology, evolution, and through mathematical modeling. Patterns may vary among distinct body parts such as the head, trunk or tail. As large amounts of photographic data is becoming more easily available, there is a growing need for general quantitative methods for capturing and analyzing the full complexity and details of pattern variation. Detailed information on variation in color pattern elements is necessary to understand how patterns are produced and established during development, and which evolutionary forces may constrain such a variation. Here, we develop an approach to capture and analyze variation in melanistic color pattern elements in leopard geckos. We use this data to study the variation among different body parts of leopard geckos and to draw inferences about their development. We compare patterns using 14 different indices such as the ratio of melanistic versus total area, the ellipticity of spots, and the size of spots and use these to define a composite distance between two patterns. Pattern presence/absence among the different body parts indicates a clear pathway of pattern establishment from the head to the back legs. Together with weak within-individual correlation between leg patterns and main body patterns, this suggests that pattern establishment in the head and tail may be independent from the rest of the body. We found that patterns vary greatest in size and density of the spots among body parts and individuals, but little in their average shapes. We also found a correlation between the melanistic patterns of the two front legs, as well as the two back legs, and also between the head, tail and trunk, especially for the density and size of the spots, but not their shape or inter-spot distance. Our data collection and analysis approach can be applied to other organisms to study variation in color patterns between body parts and to address questions on pattern formation and establishment in animals.

In the Line of Fire: Debris Throwing by Wild Octopuses

Wild octopuses at an Australian site frequently propel shells, silt, and algae through the water by releasing these materials from their arms while creating a forceful jet from the siphon held under the arm web. These "throws" occur in several contexts, including interactions with conspecifics, and material thrown in conspecific contexts frequently hits other octopuses. Some throws appear to be targeted on other individuals and play a social role, as suggested by several kinds of evidence. Such throws were significantly more vigorous and more often used silt, rather than shells or algae, and high vigor throws were significantly more often accompanied by uniform or dark body patterns. Some throws were directed differently from beneath the arms and such throws were significantly more likely to hit other octopuses. Throws targeted at other individuals in the same population, as these appear to be, are the least common form of nonhuman throwing.

Visual perception and camouflage response to 3-D backgrounds and cast shadows in the European cuttlefish Sepia officinalis

To conceal themselves on the seafloor European cuttlefish Sepia officinalis express a large repertoire of body patterns. Scenes with 3-D relief are especially challenging because neither is it possible to directly recover visual depth from the 2-D retinal image, nor for the cuttlefish to alter its body shape to resemble nearby objects. Here we characterise cuttlefish's camouflage responses to 3-D relief, and to cast shadows, which are complementary depth cues. Animals were recorded in the presence of cylindrical objects of fixed (15mm) diameter, but varying in height, greyscale and strength of cast shadows, and to corresponding 2-D pictorial images. With the cylinders the cuttlefish expressed a ‘3-D’ body pattern, which is distinct from previously described Uniform, Mottle, and Disruptive camouflage patterns. This pattern was insensitive to variation in object height, contrast, and cast shadow, except when shadows were most pronounced, in which case the body patterns resembled those used on the 2-D backgrounds. This suggests that stationary cast shadows are not used as visual depth cues by cuttlefish, and that rather than directly matching the 2-D retinal image, the camouflage response is a two-stage process whereby the animal first classifies the physical environment and then selects an appropriate pattern. Each type of pattern is triggered by specific cues that may compete allowing the animal to select the most suitable camouflage, so the camouflage response is categorical rather than continuously variable. These findings give unique insight into how an invertebrate senses its visual environment to generate the body pattern response.

Behaviour and body patterns of Octopus vulgaris facing a baited trap: first-capture assessment

This study highlights for the first time individual differences in ethology and vulnerability of Octopus vulgaris (i.e. body postures, movements and skin displays) facing passive baited traps. Common octopus exposed to a baited trap during three consecutive first-capture tests exhibited diverse behavioural and body pattern sequences resembling when the octopus searches for and hunts its wild prey. Overall, they first visually recognized new objects or potential preys and rapidly moved out of the den, exploring, grabbing and approaching the trap with the arms (chemotactile exploration), and capturing the bait with the arms and feeding on top over long periods inside the trap. Simultaneously, O. vulgaris displayed diverse skin textural and chromatic signs, the regular pattern being the most frequent and long-lasting, followed by broad mottle, passing cloud and dark patterns. All individuals (n=8) caught the bait at least once, although only five octopuses (62.5%) entered the trap in all three tests. In addition, high variability among individuals was observed regarding behaviour and body patterns during the first-capture tests, which might evidence different individual temperaments or life-history traits. Differences in behavioural responses at individual level might have population consequences due to fisheries-induced selection, although there is a high necessity to assess how behavioural traits might play an important role in life-history traits of this species harvested by small-scale trap fisheries.

Capturing and analyzing pattern diversity: an example using the melanistic spotted patterns of leopard geckos

Animal color patterns are widely studied in ecology, evolution, and through mathematical modeling. Patterns may vary among distinct body parts such as the head, trunk or tail. As large amounts of photographic data is becoming more easily available, there is a growing need for general quantitative methods for capturing and analyzing the full complexity and details of pattern variation. Detailed information on variation in color pattern elements is necessary to understand how patterns are produced and established during development, and which evolutionary forces may constrain such a variation. Here, we develop an approach to capture and analyze variation in melanistic color pattern elements in leopard geckos. We use this data to study the variation among different body parts of leopard geckos and to draw inferences about their development. We compare patterns using 14 different indices such as the ratio of melanistic versus total area, the ellipticity of spots, and the size of spots and use these to define a composite distance between two patterns. Pattern presence/absence among the different body parts indicates a clear pathway of pattern establishment from the head to the back legs. Together with weak within-individual correlation between leg patterns and main body patterns, this suggests that pattern establishment in the head and tail may be independent from the rest of the body. We found that patterns vary greatest in size and density of the spots among body parts and individuals, but little in their average shapes. We also found a correlation between the melanistic patterns of the two front legs, as well as the two back legs, and also between the head, tail and trunk, especially for the density and size of the spots, but not their shape or inter-spot distance. Our data collection and analysis approach can be applied to other organisms to study variation in color patterns between body parts and to address questions on pattern formation and establishment in animals.

Systematics, Phylogeny, and Evolution of Phrynocephalus (Superspecies przewalskii) (Reptilia: Agamidae)

The superspecies przewalskii group of Phrynocephalus includes several taxa with unclear taxonomic status. We analyze a fragment of the mitochondrial DNA gene COI and the body patterns of 275 specimens including type specimens. The results resolve the taxonomy and phylogeny of the group and we provide a diagnostic key for the species.

A study on East-Asian designations of pufferfish

In ancient Korea, pufferfish were called “복” or “복어,” whereas they have been called “hétún” (河豚) since the Ming dynasty in China, and were called “fugu” in ancient Japan. Since the introduction of the Chinese term “hétún” (河豚) into Korean and Japanese, pufferfish in Korea, China, and Japan have all been named “河豚.” Besides “하돈” (the Korean pronunciation of 河豚), pufferfish have been given various designations, such as the following: “후태” (鯸鮐) or “반어” (斑魚) based upon body patterns; “후이” (鯸鮧)” or “호이” (鰗鮧) by shape; and “기포어” (氣泡魚), “취두어” (吹肚魚), and “布久” by the look of its swollen belly. Other designations, such as “검돈” (黔魨), “작돈” (鵲魨), “활돈” (滑魨), “とらふぐ,” “からす,” and “ヒガンフグ,” were derived from pufferfish species, and designations like “진어” (嗔鱼) and “てっぽう” that originated from their habit also exist. As above, “복어” has various designations in each of the three countries, Korea, China, and Japan. These designations, composed of Chinese characters, influenced the others, and each country and ethnic group helped to form or transform new vocabularies. In particular, numerous terms concerning object designations in the forms of Chinese characters reveal hidden definitions of the ethnic groups and cultures in these designations. This study is focused on puffer designations in Korea, China, and Japan, how the puffer was named in each country from ancient through to modern times, and where the designations originated, and tries to determine the characteristics of each country’s puffer designations through investigation of the species and types of “pufferfish.”

A study on East-Asian designations of pufferfish

In ancient Korea, pufferfish were called “복” or “복어,” whereas they have been called “hétún” (河豚) since the Ming dynasty in China, and were called “fugu” in ancient Japan. Since the introduction of the Chinese term “hétún” (河豚) into Korean and Japanese, pufferfish in Korea, China, and Japan have all been named “河豚.” Besides “하돈” (the Korean pronunciation of 河豚), pufferfish have been given various designations, such as the following: “후태” (鯸鮐) or “반어” (斑魚) based upon body patterns; “후이” (鯸鮧)” or “호이” (鰗鮧) by shape; and “기포어” (氣泡魚), “취두어” (吹肚魚), and “布久” by the look of its swollen belly. Other designations, such as “검돈” (黔魨), “작돈” (鵲魨), “활돈” (滑魨), “とらふぐ,” “からす,” and “ヒガンフグ,” were derived from pufferfish species, and designations like “진어” (嗔鱼) and “てっぽう” that originated from their habit also exist. As above, “복어” has various designations in each of the three countries, Korea, China, and Japan. These designations, composed of Chinese characters, influenced the others, and each country and ethnic group helped to form or transform new vocabularies. In particular, numerous terms concerning object designations in the forms of Chinese characters reveal hidden definitions of the ethnic groups and cultures in these designations. This study is focused on puffer designations in Korea, China, and Japan, how the puffer was named in each country from ancient through to modern times, and where the designations originated, and tries to determine the characteristics of each country’s puffer designations through investigation of the species and types of “pufferfish.”

Research findings of an relocatable small size pontoon pier interaction with the aquatic medium during its towing

Использование мобильных малогабаритных причалов дает возможность при снижении затрат организовать погрузку лесоматериалов на суда в пунктах отправления с помощью техники лесозаготовителей. Это создает предпосылки для существенного увеличения объемов перевозки лесоматериалов более дешевым водным транспортом, обеспечивает экономическую доступность древесного сырья, основная часть которого находится в удаленных лесных массивах. Предполагается, что при эксплуатации мобильных причалов они нередко будут перемещаться с одного пункта погрузки на другой в условиях небольших рек с помощью судов малой мощности. Для выполнения расчетов, связанных с указанным перемещением, нужны достаточно точные сведения о сопротивлении воды движению причалов при наличии влияния дна. При теоретическом исследовании установили факторы, влияющие на величину сопротивления воды равномерному перемещению причала. Представили соответствующую зависимость в символьном виде. Преобразовали ее, получив зависимость в безразмерном виде. Обосновали возможность исключения из числа определяющих факторов числа Рейнольдса и целесообразность фиксирования факторов, характеризующих форму подводной части причала. Полученное в результате символьное решение - зависимость коэффициента сопротивления воды от относительной глубины и числа Фруда. Опираясь на нее, провели эксперименты на модели с обеспечением физического подобия. По данным эксперимента получена регрессионная модель, позволяющая вычислять коэффициент сопротивления воды равномерному движению причала, а по величине этого коэффициента определять с использованием формулы Ньютона значение силы сопротивления. Анализируя регрессионную модель, установили, что изменение скорости буксировки относительно воды от 0,5 до 1,5 м/с и соответственно числа Фруда приводит к увеличению коэффициента сопротивления на 20…25%. Изменение относительной глубины от 4,0 до 1,5 вызывает увеличение указанного коэффициента на 110…120%. Столь существенное влияние мелководья в данном случае объяснили наличием постепенно сужающей области между днищем причала и дном водоема, что приводит к более значительному увеличению относительной скорости в задней части причала. Полученная информация дает возможность наилучшим образом спланировать мероприятия, связанные с буксировкой причалов от одного пункта перевалки грузов к другому. Appliance of the relocatable small-sized pontoon piers allows to use the logging machinery for loading of the round wood at the sites of shipment. It enables to increase volumes of the timber transportation volumes using relatively unexpensive water transport and provides better access to the raw wood resources placed at the remote wood stands. It is suggested that the mobile pontoon piers will be replaced from one loading site at the small-scale shallow river to another, using the small-sized tugboats. In order to make projections of these towing operations, the reliable information regarding water resistance to the pontoons motion is needed, taking into consideration the low depths conditions. The named circumstances justify necessity of the mentioned research. As a part of the theoretical study, the factors affecting the resistance of water to uniform velocity motion of a pontoon were characterized. The corresponding dependence was presented in the symbolicand dimensionless forms. The reasons for exclusion of the Reynolds number and fixing of the of a pontoon underwater body patterns were justified. The resulting symbolic form establishes dependence of water resistance coefficient from relative depth and the Froude number. Based upon the developed equation, the model experiments were proceeded. The regression model for calculation of the resistance coefficient and consequently, using the Newton equation, the force of hydraulic drag - was developed. Variation of the towing speed (related to water) from 0.5 to 1.5 m/sec. and, consequently, increase of the Froude number, lead to 20…25% raise of the coefficient of resistance. The relative depth decrease from 4.0 to 1.5 causes 110…120% increase of the mentioned coefficient. Such a sufficient impact of shallowness is explained by increase of the relative velocity in the afterbody zone of a pontoon. The acquired information allows to improve planning of towing operations during relocation of the pontoon piers from one loading site to another.