Brown Algae

At the tip of each giant kelp frond is found the apical scimitar blade, the site of the meristem or persistent growth zone. Here the kelp's floats and blades differentiate and split apart as the kelp grows toward the surface of the sea. Depth 3 m.

These algae were found in shallow water. Padina is a calcareous alga. Caulerpa is chemically defended.

This is a female reproductive frond of the kelp floating on the surface and phot.ographed in August. It shows the meiotically produced developing eggs. When these are released and fuse with sperm from a male plant another diploid thallus results. The alga's holdfast is anchored to the sea floor. This life cycle contrasts with that of most kelps in which the diploid thallus alternates with a microscopic haploid sexual phase.

This image shows predominately the floats of the alga.

This alga has a high concentration of sulphuric acid and malic acid; the acids may deter grazers. Also, they discolor the pigments in other algae if they are placed in the same container.. Photographed at 12 m depth.

The thallus of this perennial brown alga is being swept horizontally by the ocean's surge. The holdfast anchors the kelp at a depth of 15 m. A short, tough stipe bears flattened blades. From the tips of the blades each year the alga will send slender reproductive fronds to the sea surface where eggs or sperm will be released. Fertilization will lead directly to another thallus.

Holdfast

Photographed in shallow water.

Durvillaea antarctica or Cochayuyo is a large, robust bull kelp species and the dominant seaweed in southern New Zealand and Chile. D. antarctica has a circumpolar distribution between the latitudes of 29S (in Chile) and 55S (on Macquarie Island). It is found on exposed shores, especially in the northern parts of its range, and attaches itself with a strong holdfast. D. antarctica, an alga, does not have air bladders, but floats due to a unique honeycomb structure within the alga's blades, which also helps the kelp avoid being damaged by the strong waves.

Durvillaea antarctica or Cochayuyo is a large, robust bull kelp species and the dominant seaweed in southern New Zealand and Chile. D. antarctica has a circumpolar distribution between the latitudes of 29S (in Chile) and 55S (on Macquarie Island). It is found on exposed shores, especially in the northern parts of its range, and attaches itself with a strong holdfast. D. antarctica, an alga, does not have air bladders, but floats due to a unique honeycomb structure within the alga's blades, which also helps the kelp avoid being damaged by the strong waves.

This calcareous brown alga was growing on a sunken shipwrect in the lagoon.

This subtidal view shows the alga's terminal blade located at the end of a long stipe. The alga can form an understory canopy beneath that of giant kelp.