Sperm storage and mating in the deep-sea squid Taningia danae Joubin, 1931 (Oegopsida:Octopoteuthidae)

Spermatangium implantation is reported in the large oceanic squid Taningia danae, based on ten mated females from the stomachs of sperm whales. Implanted spermatangia were located in the mantle, head and neck (on both sides) or above the nuchal cartilage, under the neck collar and were often associated with incisions. These cuts ranged from 30 to 65 mm in length and were probably made by males, using the beak or arm hooks. This is the first time wounds facilitating spermatangium storage have been observed in the internal muscle layers (rather than external, as observed in some other species of squid). The implications of these observations for the mating behavior of the rarely encountered squid T. danae are discussed

Biochemical characteristics and antibiotic properties of the mucous envelope of the queen parrotfish

The mucous cocoon of the queen parrotfish is an extensive disulphate bonded network of small glycoproteins of about 21 kDa apparent molecular weight. N-terminal amino acid sequencing revealed a unique sequence of the first 25 amino acids. Sonicated samples of mucus and the dialysed newly discovered protein inhibit bacterial growth. (C) 1999 The Fisheries Society of the British Isles

How the body contributes to the wake in undulatory fish swimming: Flow fields of a swimming eel (Anguilla anguilla)

Undulatory swimmers generate thrust by passing a transverse wave down their body. Thrust is generated not just at the tail, but also to a varying degree by the body, depending on the fish's morphology and swimming movements. To examine the mechanisms by which the body in particular contributes to thrust production, we chose eels, which have no pronounced tail fin and hence are thought to generate all their thrust with their body. We investigated the interaction between body movements and the flow around swimming eels using two-dimensional particle image velocimetry. Maximum flow velocities adjacent to the eel's body increase almost linearly from head to tail, suggesting that eels generate thrust continuously along their body. The wake behind eels swimming at 1.5 L s-1, where L is body length, consisted of a double row of double vortices with little backward momentum. The eel sheds two vortices per half tail-beat, which can be identified by their shedding dynamics as a start-stop vortex of the tail and a vortex shed when the body-generated flows reach the 'trailing edge' and cause separation. Two consecutively shed ipsilateral body and tail vortices combine to form a vortex pair that moves away from the mean path of motion. This wake shape resembles flow patterns described previously for a propulsive mode in which neither swimming efficiency nor thrust is maximised but sideways forces are high. This swimming mode is suited to high manoeuvrability. Earlier recordings show that eels also generate a wake reflective of maximum swimming efficiency. The combined findings suggest that eels can modify their body wave to generate wakes that reflect their propulsive mode

Daily carbon, nitrogen and phosphorus budgets for the Mediterranean planktivorous damselfish Chromis chromis

The planktivorous damselfish Chromis chromis is one of the most numerous fish species in the Mediterranean rocky littoral, yet the role this species plays in the overall functioning of the ecosystem is poorly understood. In this study nitrogen, carbon and phosphorus budgets were constructed for C. chromis from the Bay of Calvi, Corsica and an attempt was made to resolve the possible fates of these nutrients from ingested materials, to somatic growth (P-s), reproductive tissues (P-r), respiration (R), assimilation (A'), faeces (F) and dissolved wastes (U). C. chromis were estimated to consume on average 4.7% of their own body mass of zooplankton per day, in two separate feeding episodes - at dawn and at dusk. This is equivalent to 8288 individual copepods or 42.1 mg carbon, 9.7 mg nitrogen, 0.8 g phosphorus. 44% of all phosphorus ingested was shown to be excreted as dissolved waste, and 46% as faeces; this may be of considerable importance in the Mediterranean, where littoral macrophytes are often severely phosphorus-limited. 85% of all nitrogen was excreted as dissolved waste (mostly ammonia) and local nutrient enrichment may enhance littoral primary productivity, particularly around C chromis night-shelters. (C) 2007 Elsevier B.V All rights reserved

Lubricating the swordfish head

The swordfish is reputedly the fastest swimmer on Earth. The concave head and iconic sword are unique characteristics, but how they contribute to its speed is still unknown. Recent computed tomography scans revealed a poorly mineralised area near the base of the rostrum. Here we report, using magnetic resonance imaging and electron microscopy scanning, the discovery of a complex organ consisting of an oil-producing gland connected to capillaries that communicate with oil-excreting pores in the skin of the head. The capillary vessels transport oil to abundant tiny circular pores that are surrounded by denticles. The oil is distributed from the pores over the front part of the head. The oil inside the gland is identical to that found on the skin and is a mixture of methyl esters. We hypothesize that the oil layer, in combination with the denticles, creates a super-hydrophobic layer that reduces streamwise friction drag and increases swimming efficiency