Euglenids, Haptophytes, chromalveolates

How euglenids evolved

via the absorbtion of a green algae by a unicellular protist

euglenid structure

one short one long flagellum, red eyespot, contractile vacuole to regulate water balance, nucleus, surrounded by a pellicle

pellicle

A flexible layer that maintains the shape of euglenids and provides structural support. proves the endosymbiosis theory of euglenids

Chromalveolates

gold and brown algae formed by secondary endosymbiosis of red algae. can have a stipe.

stipe

A supporting stalk-like structure found in some algae, connecting the holdfast to the fronds.

Haptophytes

an algae clade, which was formed when a protist engulfed red algae. marine algae abundant off the coast of Britain in the north sea and the north atlantic since the cretaceous period. one example of this is the white cliffs of dover are made the skeletons of coccolithus, a subtype of haptophytes that produce calcium carbonate plates.

Coccolithus

algae surrounded by coccolithophorids, which are calcium carbonate plates produced in the cell and extruded to provide them with structural support. When the algal cell dies the calcite crystals are released into the ocean, contributing to sediment formation. Coccolithus also has two flagella, a haptonema, chloroplast, nucleus

Dinoflaggelates

a clade of Chromalveolates. mostly marine algae with cellulose theca plates for protection. two grooves in the centre house flagellla which allow multidirectional navigation. fed by phagotrophy and photosynthesis, can be an endosymbiont for corals 

red tide

highly toxic algal bloom caused by dinoflagellates, leading to harmful effects on marine life and human health. occurs more frequently due to high pollution run off into the ocean.

Plasmodium

protist which originated from dinoflagellates, responsible for malaria transmission via mosquitoes.

Diatoms

microscopic chromalveolate algae with silica (glass) cell walls, found in various aquatic environments. Thought to have evolved during the cretaceous due to loss of calcium carbonate in the ocean. Silica plates have valves and girdle bands to enable gas exchange. Mitotic reproduction inside the cell results in ongoing reduction in size until a certain minimum size is reached, after which a spore is released to restore size.

Phaetophyta

Brown algae, largest and most complex of algae with diverse tissues e.g. oe similar to phloem. usuallly marine. meiosis→ haploid spore → diploid → fusion = reproduction. can have air bladders, stipe, holdfast, lamina, conceptacles