Thursday, September 18, 2008

Life photo meme: Green algae

Kingdom: Protozoa

Phylum: Chlorophyta

Class: Ulvophyceae

Order: Ulvales

Family: Ulvaceae

I've posted this photo before, and talked about the encrusting organisms that live on it. Today I want to focus on the substratum itself, the green algae Ulva. Belonging to the phylum Chlorophyta, or the green algae, this group is considered the basal group for land plants. They share the same chlorophyll pigments, store starch, and posses cellulose cell walls.

Ulva is an interesting algae, it grows in large sheet-like patches only two cells thick. The sheets are often ruffled and fluted making its common name, sea lettuce, an apt descriptor. It attaches to rocks, docks, and other structures by a very small disk.

It also has a very interesting life cycle termed alternation of generations. The diploid generation makes spores which grow into a haploid adult without fertilization. The halpoid adult (n) makes gametes which are fertilized and grow into a diploid adult (2n). Repeat the cycle. There are lots of algae that have this type of life cycle, but Ulva is one of the only ones where you cannot tell if the adult is haploid or diploid by looking at it.

(Click here for full size image)


Kate said...

THIS is the slimy stuff floating around the beach at Cabrillo? It's a lot more interesting than I imagined!

oliemadottie said...

Kids always love this stuff when exploring the dock - I'll have to look for bryozoans next time, we usually find little polychaetes in mud casings amongst the furls!

Eric Heupel said...

Ulva is a pretty cool one. what I love about it is that it is often the substrate for so many other creatures.