Journal of the Marine Biological Association of the United Kingdom

The hypothesis of a locomotor role for the free rays of Trigloporus lastoviza is supported by: (1) their periodic retraction and protraction during slow displacement over the substratum whenever the propulsive body wave responsible for swimming is not visible; (2) the integration of the rays' individual cycles into a hexapod gait apparently generated by a metachronal impulse; and (3) the kinematic features of the longest free ray in relation to the bottom-walking velocity.

On hatching, larvae of herring, Clupea harengus L., showed increased activity to washings and extracts of the nauplii of Balanus balanoides and to glycine and proline whichare major constituents of the free amino acid pool of Balanus. Older larvae, which were fed on the nauplii of Anemia salina, showed a response to extracts, but not to washings, of this prey; they also responded to six amino acids. The active constituents of prey extracts were found to be dialysable. Surgical section showed the olfactory system was responsible for behavioural responses in herring larvae of 21 mm (total length) to extracts of Anemiasalina. At all stages of larval life, herring showed increased activity to washings of other herring larvae. Juvenile herring showed a preference for a part of a tank containing water in which other juvenile herring had been held.

Specimens of Pagurus bernhardus (with and without shells) were exposed to both gradual (sinusoidal) and abrupt (square-wave) salinity fluctuations and changes in haemolymph osmolality, tissue water content and oxygen consumption monitored. Oxygen consumption was also monitored under steady-state conditions; under these conditions there was no significant difference between the rate of oxygen consumption by animals with shells and animals without shells. Oxygen consumption was found to vary with body weight according to the equation O₂ consumption = 0·292 W^0·668. During exposure to fluctuating salinities the crabs with shells were seen to increase loco-motory activity when the external medium declined to approximately 75% sea water. Haemolymph osmolality values followed the same pattern of change as the external medium; the haemolymph of crabs without shells became significantly more dilute during exposure to low salinity than did that of crabs with shells. P. bernhardus showed significant increases and decreases in hydration level as salinities fell and rose respectively. Crabs with shells showed a marked temporary increase in oxygen consumption when the external medium declined to approximately 75% sea water; crabs without shells showed no such response. The importance of the shell as a means of protection against dilute media is discussed.

An animal-borne video camera and data-logger was used to collect behavioural data on green (Chelonia mydas) and loggerhead (Caretta caretta) turtles in Western Australia. This technique provided novel insights into the behaviour of green turtles including an apparent self-cleaning behaviour. Also, ctenophores and jellyfish might be more important in the diet of these turtles than previously thought.

Sea water probably contains all the chemical elements, although a number of them have not yet been detected. Considerable information is available on the occurrence of various elements in marine plants and animals, but it is far from complete for any one biological group. Except for recent work by Spooner (1949), on the absorption of radioactive strontium and yttrium by marine algae, no detailed study of the trace elements in the brown algae, nor any attempt to correlate the trace elements in sea water with those in the algae, appears to have been carried out. The following is a brief résumé of the work that has been done in this field.

Mối quan hệ giữa chiều dài-trọng lượng, các thông số tăng trưởng và tỷ lệ tử vong củaAnadara granosatrong vùng triều tại Balik Pulau, Đảo Penang, Bờ Tây Malaysia đã được điều tra dựa trên dữ liệu tần suất chiều dài hàng tháng (tháng 12 năm 2011 đến tháng 11 năm 2012). Tổng cộng có 548 cá thể có kích thước từ 11,25 đến 33,13 mm đã được phân tích. Quan hệ logarit giữa chiều dài và trọng lượng là Log W = 2.328 Log L − 2.537 (R² = 0.922) cho cả hai giới. Từ phương trình này, rõ ràng rằng giá trị ' b' choA. granosacho thấy sự tăng trưởng âm tính dị hình (b < 3). Một hàm tăng trưởng Bertalanffy với chiều dài tiệm cận (L_∞) là 35,40 mm và hằng số tăng trưởng (K) là 1,1 năm⁻¹ đã được thiết lập từ các phân phối tần suất chiều dài. t₀ (−0,140) được ước tính bằng cách thay thếL_∞ và Ktrong phương trình Pauly. Các kích thước đạt được củaA. granosalà 10,13, 14,36, 17,89, 20,82, 23,56 và 25,29 mm vào cuối các tháng 2, 4, 6, 8, 10 và 12, tương ứng. Chỉ số hiệu suất tăng trưởng ước tính (Ø) là 3,13 trong khi tuổi thọ ước tính của hến là khoảng 2,72 năm tại khu vực nghiên cứu. Giá trị tử vong tổng cộng ước tính dựa trên đường cong đánh bắt chuyển đổi chiều dài là Z = 3.02 năm⁻¹. Tỷ lệ tử vong tự nhiên (M) và tỷ lệ tử vong do đánh bắt (F) lần lượt là 1,84 và 0,48 năm⁻¹. Mức độ khai thác (E) của A. granosalà 0,20, điều này chỉ ra áp lực đánh bắt nhẹ lên nguồn tài nguyên.

Forty-three species of choanoflagellates were seen during a study of the heterotrophic nanoflagellates in Southampton Water, between 1991 and 1994. The majority of the species were loricate choanoflagellates (Acanthoecidae), and this group accounted for –8% of the total heterotrophic nanoplankton during the period of study. Aloricate choanoflagellates (Codosigidae and Salpingoecidae) were less diverse, and accounted for only 3–4% of the heterotrophic nanoplankton. The seasonal occurrence of loricate choanoflagellates was studied using light microscope whole mounts, whilst more detailed studies of lorica structure were made using electron microscope whole mounts. Two new species, described in this paper, had a markedly seasonal occurrence and were only recorded during a period of 6–10 weeks each spring.