Phytoplankton Identification Worksheet

PHYTOPLANKTON IDENTIFICATION WORKSHEET Phytoplankton Net used to collect the Phytoplankton Sample Follow the instructions written below: • Pipette a drop of water from the sample jar containing some of the plankton. Taking the sample from the top, bottom, and middle of the jar will help obtain different types of phytoplankton. • Place the drop of water on the slide, Vaseline could be applied on the slide to create a well for the water drop. The slide cover is gently placed on the water drop to avoid air bubbles. • Focus on the slide content using 10x magnification power. Some microscopes have a pointer that helps to identify the location of the plankton. They should observe the section now with 40x magnification power. • Draw as many phytoplankton they observe, the phytoplankton are easier to spot as they contain chlorophyll and other color pigments. The phytoplankton have characteristic green or olive brown color pigments. • Label the phytoplankton identified and classify them into the three categories of diatoms, dinoflagellates and coccolithophores. • Clean the microscopic slide and wipe the microscopic lens clean. Phytoplankton Identification Keys Diatoms (Class Bacillariophyceae) 1. They occur as single cells or in chains or other loose aggregates 2. Cell sizes can range 15 mm - 1000 mm, although most diatom sizes range from 50 to 500 mm 3. Presence of a porous, rigid cell wall (frustule) made mostly of silica 4. Presence of many small chloroplasts 5. They occur in varied shapes: circular, triangular, and modified square shapes are known as centric diatoms (shaped like pillboxes), whereas the elongated ones (bilateral symmetry) are termed pennate diatoms 6. They may possess spines or other projections that increase their surface area 7. Some common representatives of centric diatoms: Coscinodiscus, Chaetoceros (chain), Thalassiosira(chain), Pseudoeunotia (chain), Asteromphalus, Arachnoidiscus, Navicula (chain), and Triceratium. Diatoms Dinoflagellates (Class Dinophyceae) 1. They occur as single cells, rarely in chains or other aggregates 2. Cell sizes range from 25 to 1000 mm, generally smaller than diatoms 3. Presence of a porous cell wall made mostly of cellulose. In some armored forms, the cell wall consists of many articulating cellulose plates arranged irregularly over the cell surface 4. They possess several small chloroplasts usually located near the cell ends (a few species are not photosynthetic) 5. Typical forms have a body surface with two grooves, each having a flagellum 6. They may possess spines, horns or other projections 7. Some common unarmored (“naked”) representatives: Gymnodinium, Cystidinium, and Glenodinium. Some common armored species are Peridinium, Ceratium, Dinophysis, and Gonyaulax. Coccolithophores (Class Prymnesiophyceae) 50 MICRON IN DIAMETER. 1. They are single celled algae 2. They occur as spherical cells about 15-100 microns across, enclosed by calcareous plates called coccoliths. They are are 1/100 mm across because they are so tiny they can be seen only under the electron microscope. 3.They have two golden marked pigment marks with nucleus located between them. 4. They contain chloroplasts that help carry out photosynthesis. Draw Specimens of Phytoplankton Identified on the Slide using Light Microscope and Label the Species according to the three broad categories of Phytoplankton: Diatoms, Dinoflagellates and Coccolithophores.