Diatoms

Colm Lippig

Diatoms

Diatoms are a major type of algae/plankton. Most are unicellular although they have been known to grow in colonies of different shapes and sizes like spirals. Most diatoms are motile.

A diatom colony living alongside other algae

Diatoms

Diatoms grow hydrated silica “shells” to protect themselves from harm. These cell walls often form in two pieces that fit together like a box and a lid. There is a wide diversity in how they look. Tiny pores in the silica allow for gas exchange

Different types of diatoms

Diatoms

Most of the time, diatoms reproduce asexually by mitotic cell divisions. Each daughter cell receives half the cell wall of the original diatom and then regenerates the other half. They also reproduce sexually.

The regeneration of the second piece of the cell wall causes a unique shrinking effect

Diatoms

Diatoms are capable of photosynthesis. They have unique green-brown chloroplasts. By releasing oxygen as a waste product of photosynthesis, diatoms are hugely important to aqueous life.

Most diatoms exhibit unique green-brown chloroplasts

http://www.youtube.com/watch?v=aNM3AfGPHfw&NR=1

General video on Diatoms:

A murder conviction is based on diatoms:

http://www.pbs.org/wnet/nature/episodes/crime-scene-creatures/video-diatom-detective/5208/

Review Questions

1. What type of protists are diatoms?2. What unique color do the chloroplasts of most

diatoms share?3. True or false, diatoms can be found in both fresh and

salt water.4. The asexual division of diatoms leaves each daughter

with how much of the cell wall?5. The cell walls of diatoms are made of what material?6. Although diatoms are unicellular, they have been

known to form what?