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Article evaluation: Weddell Seal
The article offers a neutral viewpoint on the Weddell seal and provides adequate information about the majority of topics relevant to the species. However, many statements had no reference links, and more inline citations are necessary throughout the article, especially in the lead section. The citations present in the article are accurate and the citation links are functional.

The lead section of the article requires more editing. Some extraneous information is presented and there are few inline citations for the information. More information on the habitat and distribution of the species would be helpful. More information about the dive and breeding behavior is also needed. Another section dedicated to conservation status and history of the species would also strengthen the article.

Some information in the diving section of the article is less relevant than other information not presented. The detail on the metabolism and mechanism of anaerobic respiration is not needed here, an embedded link to the anaerobic respiration page is all that's needed.

The article is part of the Wikispecies project in addition to the Wikipedia Commons. The article is within the scope of WikiProject Antarctica and WikiProject Mammals. The article is rated as Start-Class and Low-Importance for WikiProject Mammals.

The only discussion on the talk page is a conversation about the capitalization of seal in the article title.

The Wikipedia page goes into much more detail about the specifics of the Weddell seal than we have covered in class.

Weddell Seal Article Draft
Topics and information that need to be added to the Weddell seal article:


 * distribution
 * behavior (diving, breeding, haulout)
 * lead paragraph

Behavior
Weddell seals are commonly found on fast ice, or ice fastened to land, and gather in small groups around cracks and holes within the ice (Smith 1965). In the winter, they stay in the water to avoid blizzards, with only their heads poking through breathing holes in the ice. These seals are often observed lying on their sides when on land. They are very docile, placid animals that can be easily approached (Stirling 1969).

Weddell seals are non-migratory phocids that move regionally to follow the distribution of breathing holes in the ice between seasons (Stirling 1969). Weddell seals dive to forage for food, maintain breathing holes in fast ice, and explore to find more ice holes (Davis 2003). These seals exhibit a diurnal haul-out pattern (Lake 1996). A higher frequency of seals haul out during the afternoon, usually around 4:00 PM, because of warmer air temperatures (Lake 1996).

Breeding
Weddell seals return to fast ice colonies during the spring for birthing and breeding (Shreer). The mating season occurs during austral spring between late November and December (Stirling 1969).

Depending on the latitude it inhabits, this marine mammal gives birth from early September through November, with those living at lower latitudes giving birth earlier (Stirling 1969). Weddell seals give birth to one pup per year (Stirling 1969). Birth of the pup only takes around one to four minutes. Newborn pups weigh about 29 kg and grow to two times their weigh within their first week of life (Stirling 1969). The pups take their first swim at around one to two weeks old (Stirling 1969). They can hold their breath for five minutes, enabling them to dive to depths of 100 m (330 ft) (Stirling 1969). After six to seven weeks, they are weaned and begin to hunt independently.

The mating season occurs after pups are weaned during austral spring from late November to December (Stirling 1969). Males defend underwater territories during the breeding season and have been observed to fight (Thomas 1983). During the mating season, Weddell seals make noises loud enough to be felt through the ice. Copulation has only been observed to occur under water (Stirling 1969). The seals are normally around six to eight years old when they first breed, but this can be much earlier for some females (SOURCE??).

Weddell seals undergo delayed implantation. The embryo is not embedded into the uterus until the beginning of austral summer, between mid-January and mid-February, allowing for birth under more favorable environmental conditions. (Stirling 1969).

Diving
Weddell seals have been observed to dive as deep as 600 m for up to 43 minutes (Stirling 1969). Such deep dives involve foraging sessions, as well as searching for cracks in the ice sheets that can lead to new breathing holes. After dropping away from a breathing hole in the ice, the seals become negatively buoyant in the first 30 to 50 m, allowing them to dive with little effort as they make a “meandering descent". The seals can remain submerged for such long periods of time because of high concentrations of myoglobin in their muscles.

Weddell seals' metabolism is relatively constant during deep-water dives, so another way to compensate for functioning with a lack of oxygen over an extended period of time must exist. Seals, unlike other mammals (such as humans), can undergo anaerobic metabolism for these extended dives, which causes a build-up of lactic acid in the muscles. (FIND SOURCE THEY USED)

These seals also compensate for prolonged lack of available oxygen by increasing their oxygen-carrying capacity, which done by having more red blood cells per unit volume of blood, as well as having more blood relative to other mammals. (FIND SOURCE THEY USED) Typical oxygen concentration levels in human blood at sea level are about 15 ml/kg, where as Weddell seals can have 60 ml/kg.(FIND SOURCE THEY USED) They can also release oxygenated blood from their spleens into the rest of their bodies, acting as an oxygen reserve. (FIND SOURCE THEY USED) Other circulatory adjustments include reducing their heart rate, and blood buffering, which prevents the pH of the blood from decreasing too much. (FIND WHAT SOURCE THEY USED)

Weddell seals exhibit a diel dive pattern, diving deeper and longer during the day than at night (Kooyman 1975).