User:Daphne DSB/Oarfish

Anatomy and Morphology Edits (Daphne)
It has also been hypothesized that this hyper ossification acts as a lever for the oarfish dorsal fins, which contributes to the organism's buoyancy.

Life History Edits (Daphne)
In addition to the otolith, recent studies have revealed more information about the reproductive organs of the oarfish. Using photographs, histological cross-sections, and measurements of four samples of R. russelii, researchers were able to qualitatively describe the sexual organs of the species. These studies have shown that female oarfish have bifurcated ovaries containing a cavity through which the eggs pass before leaving the body of the oarfish. Testes on male oarfish are located in a similar place as the ovaries of female oarfish, near the digestive tract called the coelomic cavity. The oarfish have two separate, disconnected testes and the left testes observed were longer than the right testes. An analysis of these findings led researchers to conclude that R. russelii are likely batch spawning fish that produce a large number of offspring every breeding season.

Based on a study that performed an artificial insemination with the eggs and sperm from a pair of deceased R. russelii samples, the morphology of the oarfish larvae was able to be examined. This study described the larvae as having long yet compact bodies. The larvae were invertebrates but had bones in their head area, as well as fins. The swimming patterns of the larvae were analyzed, and it was determined that they primarily used their pectoral fins for motility.

Distribution Edits (Daphne)
The oarfish typically reside in the mesopelagic area of the sea.

Parasite Edits (Daphne)
A recent study concerning the parasitization of this species revealed that the shorten mako shark and the sperm whale could both be predators of the oarfish, based on pattens of parasite transmission. These conclusions were made based on analysis of the visceral tissue of an oarfish recovered by the Catalina Island Marine Institute in Santa Catalina Island, California.

Feeding Ecology (Daphne)
It has been observed that oarfish eat by suctioning prey such as plankton blooms while in the water.

Addition to Anatomy and morphology section (John)
Hyperostoic bone growth has been documented in several specimen of oarfish that have washed up on the coast of California. Hyperossified pterygiophores have been discovered to run along the entire dorsal length of oarfish. The function of this is to both provide structural support to the spine of oarfish during undulations (tail movement used for locomotion) and to remodel spines to prevent stress fractures that could occur from too much movement. Oarfish don't contain swim bladders like many deep sea fish have for maintaining depth in the water column. It is likely that this lack of a swim bladder forces more frequent tail undulations as the main mode of depth regulation in oarfish.

Phylogeny (John)
Through the analysis of the mitochondrial genome of Regalicus glesne, the phylogenetic placement of the the Giant Oarfish was further verified. Oarfish are considered Lampriformes (an phylogenetic order), and they have been placed here due to their morphology. However, analysis of the mitochondrial genome of an R. glesne specimen clusters the species with Trachipterus trachypterus and Zu cristatus, two other Lampriformes. These three species were clustered together due to similarity in genetic sequence and morphology, which further supports the phylogeny and evolution of Lampriformes.