Kelp gull

The kelp gull (Larus dominicanus), also known as the Dominican gull, is a gull which breeds on coasts and islands through much of the southern hemisphere. The nominate L. d. dominicanus is the subspecies found around South America, parts of Australia (where it overlaps with the Pacific gull), and New Zealand (where it is known as the southern black-backed gull or by its Māori name karoro). L. d. vetula (known as the Cape gull) is a subspecies occurring around southern Africa.

The specific name comes from the Dominican Order of friars, who wear black and white habits.

Description

The kelp gull superficially resembles two gulls from further north in the Atlantic Ocean, the lesser black-backed gull and the great black-backed gull and is intermediate in size between these two species. This species ranges from 54 to 65 cm (21 to 26 in) in total length, from 128 to 142 cm (50 to 56 in) in wingspan and from 540 to 1,390 g (1.19 to 3.06 lb) in weight. Adult males and females weigh on average 1,000 g (2.2 lb) and 900 g (2.0 lb) respectively. Among standard measurements, the wing chord is 37.3 to 44.8 cm (14.7 to 17.6 in), the bill is 4.4 to 5.9 cm (1.7 to 2.3 in) and the tarsus is 5.3 to 7.5 cm (2.1 to 3.0 in). The adult kelp gull has black upperparts and wings. The head, underparts, tail, and the small "mirrors" at the wing tips are white. The bill is yellow with a red spot, and the legs are greenish-yellow (brighter and yellower when breeding, duller and greener when not breeding). The call is a strident ki-och. Juveniles have dull legs, a black bill, a dark band in the tail, and an overall grey-brown plumage densely edged whitish, but they rapidly get a pale base to the bill and largely white head and underparts. They take three or four years to reach maturity.

Kelp

Kelps are large seaweeds (algae) belonging to the brown algae (Phaeophyceae) in the order Laminariales. There are about 30 different genera.

Kelp grows in "underwater forests" (kelp forests) in shallow oceans, and is thought to have appeared in the Miocene, 23 to 5 million years ago. The organisms require nutrient-rich water with temperatures between 6 and 14 °C (43 and 57 °F). They are known for their high growth rate — the genera Macrocystis and Nereocystis can grow as fast as half a metre a day, ultimately reaching 30 to 80 metres (100 to 260 ft).

Through the 19th century, the word "kelp" was closely associated with seaweeds that could be burned to obtain soda ash (primarily sodium carbonate). The seaweeds used included species from both the orders Laminariales and Fucales. The word "kelp" was also used directly to refer to these processed ashes.

Description

In most kelp, the thallus (or body) consists of flat or leaf-like structures known as blades. Blades originate from elongated stem-like structures, the stipes. The holdfast, a root-like structure, anchors the kelp to the substrate of the ocean. Gas-filled bladders (pneumatocysts) form at the base of blades of American species, such as Nereocystis lueteana, (Mert. & Post & Rupr.) to hold the kelp blades close to the surface.