Rocky Intertidal, Macroalgae,
and Arthropods
Objectives: Students will be able to
1) Locate the rocky intertidal zone and the
organisms that live there.
2) State the different stresses and adaptations
found in each zone.
Your Task – Groups of 2 at your tables
On a poster, diagram the three beach zones:
• Supratidal, Intertidal, and Subtidal
• Include the plants and animals that live in
each zone
On the flip side - Draw in and complete this table:
Zone
Supratidal
Intertidal
Subtidal
Challenges in zone
Adaptations for survival
The supratidal zone – The place where you put
your towel or blanket with you visit the beach.
This area is above the high tide line and never gets
wet. However, there is salt spray from the ocean
which limits plant growth.
The higher up you are from the high tide line, the
more plants can survive.
The intertidal zone – Located between the high
tide and low tide. At high tide, the intertidal zone
is covered with water, and at low tide, it is
exposed.
High tide is marked with a strandline – where the
water pushes seaweed and debris onto the sand.
Animals that live here are adapted for the
challenges of alternating wet and dry
environments.
The subtidal zone – Below the low tide line, always
covered in water. This area is not considered the
same as the open ocean because this is the zone
affected by heavy wave impact and underwater
turbulence (the undertow of the tide).
Challenges of each zone?
Supratidal – Salt spray, few nutrients, almost no
fresh water, blowing wind and sand.
Intertidal – Sometimes exposed to air, sometimes
covered by water.
Subtidal – Affected by heavy waves and
underwater currents.
Adaptations that organisms in each zone have:
Supratidal dune grass –
Thick, shiny leaves to prevent
water loss.
Deep, underground stems.
Symbiotic relationship with
Fungi.
http://www.montereybayaquarium.org/animal-guide/plantsand-algae/american-dune-grass
Adaptations that organisms in each zone have:
Intertidal zone organisms –
https://www.youtube.com/watch?v=ZkULAD8gJT0
Adaptations that organisms in each zone have:
Intertidal zone organisms –
Close their shells tightly to
keep water inside.
Form clusters to avoid
individual exposure.
Cling to / hide under rocks to avoid being washed away.
https://www.youtube.com/watch?v=DR1gP5S6Bsk
https://www.youtube.com/watch?v=Ofyn9aXw8sM
Adaptations that organisms in each zone have:
Subtidal zone –
Structures to help them
cling to hard rocks so they
aren’t swept away.
Flattened bodies to minimize
wave impact.
Macroalgae
Macroalgae:
•
Lack true stems, roots, leaves (lack vascular tissue)
•
Primary producers - capture light for
photosynthesis to make food
More characteristics of Macroalgae:
•
Chlorophyll and other pigments
used for photosynthesis
•
Photosynthesis done in all parts
•
Gain water by diffusion and osmosis
General Structure
Parts to list and identify:
Blade
Holdfast
Stipe
Air bladder (pneumatocysts)
Thallus
Thallus
Air Bladder
General Structure
Blade – leaf-like flattened portions
Holdfast – attaches the thallus to the bottom
Stipe – stemlike structure to provide support
Air bladder (pneumatocysts) – keep the blades close
to the surface. Gas filled = buoyant (CO-toxic)
Thallus – complete body
Seaweed is under Kingdom Protista
(^ Not animals, not plants either!)
There are three Phyla of Seaweeds that you will need to know:
Phylum Chlorophyta (Green Algae)
Phylum Phaeophyta (Brown Algae)
Phylum Rhodophyta (Red Algae)
Phylum Chlorophyta (Green Algae)
Chlorophyll is not masked by other
colors, so the thallus is green.
Ex: Sea Lettuce
Phylum Phaeophyta (Brown Algae)
Can be olive green to dark brown.
They have other pigments that
mask over chlorophyll.
Ex: Rockweed & Kelp
Phylum Rhodophyta (Red Algae)
Red pigments mask chlorophyll. They grow
in shallow water environments, and some
are harvested for food &
used in many products.
Ex: Irish Moss
Macroalgae Reproduction:
Asexual – Fragments of the thallus can break
off and grow into new individuals
Sexual –
1) spores (similar to broadcasting)
2) production of gametes
3) alternation of generations
Flip-flop between using spores or gametophytes
Economic Importance:
Mariculture = farming of Macroalgae
Seaweeds produce gelatinous chemicals that
are used in food processing and many
products that you use daily!!!
Thickening agents produced by seaweed:
Chemical compound
What does it do?
What is it in?
Algin comes from Kelp
Stabilizer and emulsifier
(keeps things from
getting “clumpy”)
Frosting / pies
Shampoo
Shaving cream
Emulsifier
Instant pudding
Ice cream
Carageenan comes from
Red Algae
Agar from Red Algae
Forms solid gel
Protects ham & fish
during canning process.
Cosmetics.
Bacteria cultures.
Phylum Arthropoda
•
•
•
•
Segmented bodies
Jointed appendages
Exoskeleton – hard outer covering
Molt – shed exoskeleton
•
•
•
Bilaterally symmetrical
Blood = hemolymph
Image forming, compound eye (good at
detecting movement, bad at detecting depth)
Kingdom: Animalia
Phylum:
Arthropoda
Sub-phylum: Crustacea = “The crustaceans”
3 Arthropod body segments
1.
Head
2.
Thorax
3.
Abdomen
VS.
2 crustacean body segments
1.
Cephalothorax
2.
Abdomen
Body parts and functions:
1. Carapace - hard exoskeleton covering cephalothorax
2. Antennae - used for sensing, touch, and balance
3. Maxilipeds - Little feeding arms
4. Mandible - jaws used for chewing food
5. Gills - absorb oxygen from the water
6. Chilipeds - claws
7. Swimmerets - egg holding and they create water current
8. Telson & Uropods - fan-like extensions for swimming
Largest group of Crustaceans: Shrimp, crab, & lobsters
Decapods - Animals that have 10 appendages (5 pairs)
Functions: Walking
Defense
Gas exchange
Don’t forget! 1st pair = Chelipeds
They are scavengers - in rocky areas
They are mostly nocturnal and benthic
Long Island Sound Examples:
Green crab
Asian
shore crab
“Maine” Lobster
Blue crab
Grass shrimp
Hermit crab
Small crustaceans:
Zooplankton - “animal drifter” - bugs and flees of the ocean
Why are they zooplankton and not phytoplankton?
This means “plant drifter”
Found on the bottom, in seaweed, or on animals
Examples:
Copepods
Barnacles
Isopods/Gribbles
Amphipods
“beach hoppers”
Krill
1st pair of
swimmerets
FEMALE
MALE
Identifying Male/Female Crabs
Male or Female?
Male or Female?
Molting
1.
Secrete enzymes that soften
the shell
2. The shell splits up the back
and the creature backs out
leaving it behind
3. They will increase their size
by about 20% at every molt.
4. After a molt “soft-shell” will
hide among the rocks for 68 weeks until they harden.
https://www.youtube.com/watch?v=4QIgW639Oog
If there is time...
http://www.youtube.com/watch?v=2PGHZDnZ0Mc 3:11
http://marinebio.org/gallery/video/sand-crabs.asp 2:15
http://www.youtube.com/watch?v=pgvsQ6oNZyo 1:40
http://www.youtube.com/watch?v=BssJIxTulrs&feature=related 5:38
http://www.youtube.com/watch?v=jmebAjdMrLs&feature=relmfu 3:39
http://www.youtube.com/watch?v=8agrODIyx2c 1:43
http://www.youtube.com/watch?v=25F7xMVNt-w 0:27