Friday, May 14, 2021

The shapes of brown algae

 Just a few low-tide seaweeds:

A baby bull kelp. Cute, isn't it?

A flat-bladed rockweed, with beauty bush.

I have been confused by the rockweeds, finding different shapes, thin ones, long pointed rockweeds, wide-bladed ones, flat-bladed rockweeds, rockweeds with the characteristic bladders that kids like to pop. But I couldn't find, in my encyclopedia, more than two species of true rockweed (Fucus sp.; they have a distinct midrib. Dwarf rockweed, less common on our shore, has no midrib.)

A few years back scientists examined the DNA of various rockweeds, finding that our local ones were mostly all the same species, Fucus distichus. Turns out it is extremely variable as to shape, depending, it seems, on the habitat.

And the fat bladders are the mature reproductive structures. The one in the photo, then, is immature.

I think this is sea caulifower, Leathesia nana. On sea lettuce.

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Unas pocas algas marinas:

Primera foto, un quelpo Nereocystis luetkeana, muy pequeño. (Crecen hasta 36 metros.)

Segunda foto: Sargazo vejigoso; Fucus distichus. Con "arbusto de belleza", Callithamnion pikeanum.

Me han dejado algo confusa los sargazos locales; vienen en una variedad de formas, delgados, o largos y puntiagudos, o con hojas anchas, hojas planas, o con las puntas infladas, haciendo los globos que los niños se apuran a reventar. Pero en mi enciclopedia encontraba nada más dos especies de sargazo "verdadero". (Fucus sp.,estos tienen un tallo central muy distinta. Otras dos especies, menos común en nuestras costas, son más pequeñas, y no tienen este tallo.)

Hace unos años, los científicos examinaron el ADN de varios de estos, y descubrieron que casi todos son de la misma especie, Fucus distichus. Resulta que es extremadamente variable en forma; parece que esto depende de su habitat.

¿Y las vejigas gordas? Son las estructuras reproductivas de las algas maduras. Así que la de la foto es todavía juvenil.

Tercera foto; la que llamamos coliflor marina, Leathesia nana. Descansa sobre una cama de lechuga marina.

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