Marine Algae Identification Laboratory
Goals:
The student will have the opportunity to acquire knowledge about marine algae.
The student will begin to recognize marine algae by name.
Objectives:
The student will draw and become familiar with marine algae.
INTRODUCTION:
The multicellular algae have many special adaptations which allow them to survive near the
shore. This shallow marine environment can pose many extremes. In the inter tidal zone the
algae must have protective devices so that they do not dry out at low tide. They must also be able
to resist being tossed or pulled off the substrates or rocks in the waves. These algae are located in
shallow waters since they are attached to the bottom by hold fasts and must receive sunlight.
They are a great food source for many herbivores. These organisms provide a valuable marine
habitat and are good indicators of the health and diversity of the marine environment. The marine
algae are very diverse and are classified into three basic groups depending upon their
photosynthetic pigments and reproductive strategies. The groups that you will be studying are
green, red and brown algae. The algae have the following main structures: the holdfast which
secures the algae to the rocks; the stipe or supporting stalks; the blades which are provide large
surfaces for photosynthesis; the air bladder which buoys the algae up in the water; the thallus
which is the main portion of the plant when it does not have stipes or blades; and the receptacle
which attaches the stipes to the holdfast.
One of the most familiar green algae is Ulva or sea lettuce. These algae are two cells thick and
loses its water during low tide. They become very crisp yet are still living. They re-absorb the
water when the tide covers it again. Two types of red algae that live in the inter tidal zone are the
encrusting and articulated coralline algae. The coralline red algae secrete a calcium carbonate or
lime in their cell walls. This makes them tough and not very editable.
The brown algae are much larger than other types of algae. Rockweed are algae, that are able
to live in the higher inter tidal zone. These algae have thallus which support small air bladders.
Another type of brown algae is the feather boa kelp or egregia has very long and wide stipes with
smaller blades and bladders attached to the side. It appears to resemble a feather boa. One other
is the bullwhip kelp with a very long sturdy stipe and large air bladder. The blades protrude from
the air bladder. This kelp grows at depths of 30 meters. The largest of the brown kelp is giant
kelp which grows in large kelp beds in deeper water. These algae can grow up to 2 feet per day.
It has large blades which grow out of air bladders which extend from the branching stipes. As
these algae grow, they can have a holdfast which is larger than meters across.
This laboratory will help you become familiar with the types of algae that you will see at the
ocean in the tide pools. You will have the opportunity to learn and recognize the algae as you
draw the organisms.
MATERIALS:
Pencil
Colored pencils
Notebook
Ruler
iPad
Brown
Marine algae
Red
Giant Kelp
Bullwhip Kelp
Rockweed
Oarweed
Feather Boa Kelp
Purple Laver
Dulse or Dillisk
Irish Moss
Carrageenan Moss
Sea Beech
Green
Sea Lettuce
Sea Grapes
Turtle Grass
PROCEDURE:
1. Go on the Internet (Google.com) and look up each of the algae listed above.
2. Draw the algae. Label the holdfast, stipes, blades, air bladders, thallus and receptacle.
Group 1:
a. In your notebook, label the top "Brown Algae".
b. Draw, color, and label the 5 brown algae listed.
c. Find and write the following online:
• Scientific name
• Physical features or characteristics
• Life cycle
• General size or shape
• Where are they found?
Group 2:
a. On another page in your notebook, label the top "Red Algae".
b. Draw, color, and label the 5 red algae listed.
c. Find and write the following online:
• Scientific name
• Physical features or characteristics
• Life cycle or lifespan
• General size or shape
• Where are they found?
Group 3:
a. On a third page in your notebook, label the top "Green Algae".
b. Draw, color, and label the 3 green algae listed.
c. Find and write the following online:
• Scientific name
• Physical features or characteristics
• Life cycle or lifespan
• General size or shape
• Where are they found?
ANALYSIS QUESTIONS:
1. What are three ways in which algae are adapted to live in the intertidal zone?
2. How are the algae important part of the food chain?
3. How are the three groups of algae alike? How are they different?