Papillomatous Skin Netting of Cetaceans (Cetacea: Delphinapterus leucas, Balaena mysticetus, and Eschrichtius robustus) and Sirens (Sirenia: Trichechus manatus and Dugong dugon).

The structure of the papillomatous junction between epidermis and dermis (papillomatous netting, PN) in the skin of cetaceans (white whales, bowhead, and gray whales) and sirens (American manatee, dugong) was studied and compared using histophysiological and morphogeometric methods. The relative extent of PN development proved to be similar in members of both orders, but significant differences were found in PN configuration, the volume of "free area of grille", the degree of skin vertical compression, and skin density, which influence buoyancy. The differences are discussed from the viewpoint of species biology.

Abundance estimate of the Okhotsk Sea population of the bowhead whale (Balaena mysticetus Linnaeus, 1758).

Abundance of 388 ± 108 whales for the Okhotsk Sea bowhead whale population based on individual genotyping was estimated using the capture-recapture method for the open population model. The data demonstrate that this endangered population shows no signs of recovery.

Serological Detection of Causative Agents of Infectious and Invasive Diseases in the Beluga Whale Delphinapterus leucas (Pallas, 1776) (Cetacea: Monodontidae) from Sakhalinsky Bay.

Serological detection of some pathogens in the beluga whale Delphinapterus leucas population from Sakhalinsky Bay of the Sea of Okhotsk (Sakhalin-Amur beluga whale stock) was performed in 2013-2014 after the largest recorded flood of the Amur River (among observations since 1896). The percent of this population that is immune to the causative agents of clonorchosis was 25.6%; toxoplasmosis, 11.5%; brucellosis, 38.5%; tuberculosis, 30.8%; cetacean morbillivirus infection, 16.7%; and to alpha and gamma herpes viruses each, 21.8%.

Summer molting of bowhead whales Balaena mysticetus Linnaeus, 1758, of the Okhotsk Sea population.

In bowhead whales summering in Ulbanskiy Bay of the Okhotsk Sea, molting of epidermis has been found and histologically confirmed. The outer layer of the molting whale epidermis is longitudinally stratified and rejected in the form of relatively large plates up to several millimeters thick, each representing a lamellar formation consisting of longitudinal rows of parakeratocytes with degenerated nuclei, numerous pigment granules, and lipid inclusions. Molting intensity is correlated with the level of proliferation and regeneration of all epidermal layers, which helps to maintain the optimal skin thickness.

[Molecular genetic analysis of the shantar summer group of bowhead whales (Balaena mysticetus L.) in the Okhotsk Sea].

The results of molecular genetic analysis (full-length sequences of the cytochrome b gene and mtDNA control region and the allelic composition of 14 microsatellite loci) of 65 tissue samples from the endangered bowhead whale (Balaena mysticetus) population in the Sea of Okhotsk are presented. The data obtained enable the suggestion that the current state of the Sea of Okhotsk bowhead whale population is rather stable.

[Rest and activity states in the Commerson's dolphin (Cephalorhynchus commersonii)].

The unihemispheric slow-wave sleep, the ability to sleep during swimming with one open eye and the absence of paradoxical sleep in the form of it is observed in all terrestrial mammals are unique features of sleep in cetaceans. Visual observations supplement electrophysiological studies and allow obtaining novel data about sleep of cetaceans. In the present study we examined behavior of 3 adult Commerson's dolphins Cephalorhynchus commersonii which were housed in the oceanarium Sea-World (San Diego, USA). The behavior of the dolphins can be subdivided into 5 swimming types: 1) active swimming marked by variable speed and irregular trajectory of movement (on average for 3 dolphins 35.1 +/- 2.7% of the 24-h period) was scored as active wakefulness; 2) circular swimming was divided into slow and fast swimming and occupied, on average, 44.4 +/- 3.8 and 9.7 +/- 0.8% of the 24-h period, respectively; while in circular swimming, dolphins swam from 1 to 6 circles on one respiration pause; 3) quiet chaotic swimming (3.9 +/- 1.2%) that occurred at the bottom and was not accompanied by signs of activity; 4) floating, and 5) slow swimming at the surface (4.1 +/- 0.5 and 2.8 +/- 0.4%), respectively; the latter two swimming types were accompanied by frequent respiration (hyperventilation). We suggest that sleep in Commerson's dolphins occurred predominantly during the circular and quiet swimming. From time to time the dolphins slowed down their speeds and even stopped for several seconds. Such episodes appeared to be the deepest sleep episodes. In all dolphins muscle jerks as well erections in the male were observed. Jerks and erections occurred during the circular and quiet chaotic swimming. Similar to other studied small cetaceans, Commerson's dolphins are in a state of almost uninterrupted swimming during 24 h per day and they sleep during swimming. Some muscle jerks that we observed in the dolphins in this study might have been episodes of paradoxical sleep.

Muscle jerks during behavioral sleep in a beluga whale (Delphinapterus leucas L.).

We conducted video recording of the behavior of one captive adult male beluga (or white) whale over eight nights aiming to quantify muscle jerks and to evaluate their relationship to the sleep-waking cycle. Presumably, the whale was asleep during a significant portion of the time it spent lying on the bottom of the pool. Individual sleep episodes lasted between 20 and 492 s and on average occupied 66.7+/-2.6% of the nighttime (n=8). Muscle jerks were quantified in the last three nights, during which an average of 144+/-24 jerks were documented per night. Forty-six percent of all jerks occurred within 10 s of each other. Series of jerks lasted 2-21 s (on average 4.8+/-0.5 s, n=97) and in total occupied 0.3-0.7% of the rest time (0.2-0.5% of total nighttime). Jerks occurred more frequently at the end of rest episodes. A significant portion of rest episodes with jerks (62%) followed each other. These series of episodes with jerks alternated with periods when jerks were not recorded over 8-37 min. We conclude that some jerks meet the behavioral criteria of paradoxical [or rapid eye movement (REM)] sleep (PS). On the other hand, definitive conclusions about the presence and duration of this sleep stage in cetaceans cannot be reached without further combined electropolygraphic studies and visual observations.

Unihemispheric slow wave sleep and the state of the eyes in a white whale.

We recorded electroencephalogram (EEG) and simultaneously documented the state of both eyelids during sleep and wakefulness in a sub-adult male white whale over a 4-day-period. We showed that the white whale was the fifth species of Cetaceans, which exhibits unihemispheric slow wave sleep. We found that the eye contralateral to the sleeping hemisphere in this whale was usually closed (right eye, 52% of the total sleep time in the contralateral hemisphere; left eye, 40%) or in an intermediate state (31 and 46%, respectively) while the ipsilateral eye was typically open (89 and 80%). Episodes of bilateral eye closure in this whale occupied less than 2% of the observation time and were usually recorded during waking (49% of the bilateral eye closure time) or low amplitude sleep (48%) and rarely in high amplitude sleep (3%). In spite of the evident overall relationship between the sleeping hemisphere and eye state, EEG and eye position in this whale could be independent over short time periods (less than 1 min). Therefore, eye state alone may not accurately reflect sleep state in Cetaceans. Our data support the idea that unihemispheric sleep allows Cetaceans to monitor the environment.

Rest and activity states in a gray whale.

The behaviour of a female gray whale (Eschrichtius robustus) that had been rescued 14 months previously was recorded continuously on a video-recorder for 9 days at 'Sea World' in San Diego. On average, during the first six recording days, active wakefulness accounted for 37.9 +/- 1.7% of each 24 h; transitional stage for 17.4 +/- 1.4% and rest for 41.2 +/- 1.7%. In the rest stage the whale was lying on the bottom of the pool (13.2 +/- 1.7%) or hanging on the surface (28. 0 +/- 1.7%). During the rest stage, it was immobile most of the time and moved only for respiration. In the rest stage both eyes could be open, one eye could be open while the other was closed or, more rarely, both eyes could be closed. Characteristic jerks of the head, neck and sometimes of the whole body were observed in the whale during the rest stage. Most jerks were single and only 10% of all jerks were serial (occurring within 10 s of a prior jerk). Eyelid movements accompanied 40% of jerks. In two episodes, intense jerks followed each other continuously for 3 and 4 s and were accompanied by eyelid movements. These jerks resembled the twitches characteristic of paradoxical sleep in terrestrial mammals. During these episodes the whale was falling slowly onto its side and subsequently started to swim in the pool.