Euglenophyta, Cryptophyta and Haptophyta

Outline

Euglenophyta

Introduction

a.k.a. euglenoids

mostly unicellular, freshwater

Cells

Flagella --

• two of 'em -- short and long
• originate in reservoir
• eyespot -- associated with flagellar swelling

Pellicle

• proteinaceous, flexible
• euglenoid motion

Chloroplasts -- typically:

• chlorophylls a and b + carotenoids
• 3 membranes
• thylakoids in stacks of three
• paramylon = reserve polysaccharide

Nucleus -- weird

"mesokaryotic" nucleus

chromosomes always condensed

mitosis

• nuclear envelope persists (closed mitosis)
• spindle apparatus microtubules form inside nucleus -- organized by basal bodies of flagella
• cell division is longitudinal

Life cycle -- no sexual reproduction

Ecology

habitat & nutrition

• freshwater, but with high organic content
• 1/3 autotrophic -- actually auxotrophic
• 2/3 heterotrophic

Cryptophyta

Intro

12 genera

primarily unicellular flagellates

mixotrophic

Cells

flagella --2, both tinsel

gullet -- allows ingestion

periplast

• proteinaceous outer covering
• has trichocysts

chloroplast

• chls a and c
• phycoerythrin and phycocyanin (colored)
• 4 chloroplast membranes

  nucleomorph -- reduced eukaryotic nucleus

Ecology

phytoplanktonic

Mesodinium

a ciliate with a reduced cryptophyte endosymbiont

Haptophyta

Intro

a.k.a. Prymnesiophyta

about 500 spp.

mostly unicellular flagellates (also multicellular, filamentous and nonflagellated)

Cells

flagella

2 smooth

haptonema

flexible, with microtubules, for capture of prey

scales

organic and/or calcified (covered in CaCO₃)

Coccolithophorids -- nonflagellated, with calcified scales

chloroplast

• chls a and c
• fucoxanthin
• thylakoids in 3's
• 4 membranes
• store chrysolaminarin in vesicle

  -- related to heterokont chloroplast (?)

Life cycle

varied, often change morphology in different stages

Ecology and importance

primary producers

coccolithophorids et al. important in ocean

calcium carbonate (CaCO₃) deposition

chalk deposits, takes CO₂ from atmosphere

dimethyl sulfide (DMS) production

cloud formation

toxic or annoying blooms

Vocabulary

click here to go to miscellaneous algae vocabulary