SWES 475/575 Class Notes – Thursday, February 5, 2004

 

Green Algae 2 – Chapter 18

 

Ulvophyceans – marine, green seaweeds, also freshwater lakes and streams

           

            - Some siphonous (siphon = “tube”)

            - coenocytic – multinucleate to all one cell

            - 100 genera, 1100 spp.

            - simple            complex

 

            Ulotrichales

            filaments to blades

            Monostroma –

                        eaten in Japan

                        life cycle: single layer blade                    gametes          zygote   meiosis

                                    codiolum stage (2N)     meiosis    zoospores (?)               blade

            Ulothrix –

                        filament w/ zoosporangium or gametangium

                        2 gametes                     fusion               resting zygote

            Ulvales –

                        Ulva - “sea lettuce”

                        sheet (2 cell layers)

                        Enteromorpha

                        tube (2 cell layers)

            isomorphic alternation of generations

            Siphonocladeles –

                        Cladophora – multinucleate

                                    several meters

                                    found: Lee’s Ferry, Maui

                        Dictyosphaeria –

                                    multinucleate walled cells

            Caulerphales – “beautiful forms”

                        siphonous (1 cell only)

                        Up to several meters, complex body plans

                        Bryopsis – feathery laterals

                        Codium – “dead man’s fingers”

                                    spongy, green

                        Caulerpa –

                                    plant-like with shoots and rhizoids

                                    spreading in Mediterranean and California(Caulerpa taxifolia)

            Dasycladales –

                        siphonous to uninucleate

                        Hallimeda (looks like prickly pear cactus)

                                    calcareous coat – reef building, some mounds 50m thick

                                    can grow 6m/ 1000 years

                        Acetabularia- umbrella algae

-         Mass spawning

why siphonous?

1997- Clifton – corals, gorgonians

now – siphonous greens

Mar- July, pre-dawn

green gametes, clear body

males first, then females

swim for 1 hour, 100cm

green clouds of zygotes

settle on bottom, grow

                        unlike corals, not related to tides/ lunar cycles