Structure of a Typical Marine Alga
• Absorption of water and nutrients occurs throughout the thallus, so there is no conducting tissue
• Holdfast: root-like structure that secures seaweed to substrate
• Stipe: stem-like structure that allows the blades to reach sunlight and absorbs shock by bending with waves
• Blade: leaf-like structure, symmetrical with equal stomata and chlorophyll on both sides. Contains reproductive structures.
Algae Structure, cont.• Air bladder: also called pneumatocyst, hollow CO filled
floats. In brown algae (kelp) only, holds blades close to the light at the surface.
Phylum Chlorophyta: Green Algae
• Chlorophyll = green
• 10% marine, upper intertidal
• Examples:
• Ulva (sea lettuce)
• Cladophora
• Codium (dead man’s fingers)
Phylum Phaeophyta: Brown Algae
• Largest and most complex
• Chlorophyll masked by fucoxanthin
• Examples:• Fucus
(Rockweed)• Macrocystis
(Kelp)• Laminaria
(Oarweed)
Phylum Rhodophyta: Red Algae
• Chlorophyll masked by phycoerythrin
• Subtidal to 200m• Examples:• Gigartina (Turkish
Towel)• Corraline Algae• Porphyra (Nori)
Ulva Life Cycle•2n = diploid•1n = haploid•Sporophyte produces spores by meiosis•Spores grow into gametophyes•Gametophyte produces gametes by mitosis•Sporophyte identical to gametophyte•Zygote, a result of fertilization, a union of gametes, grows into sporophyte
Kelp Life Cycle• Sporophyte produces
spores by meiosis• Spores grow into
gametophytes• Gametophytes
produce gametes by mitosis
• Sporophyte is large, gametophyte is microscopic.
• Gametes unite into zygote which grows into sporophyte.
Seagrasses• The only marine
flowering plants• Have true roots,
stems and leaves• Live completely
submerged• Pollen release is
timed to coincide with spring tides
• Seeds have bristles for attachment
• Can reproduce asexually by rhizomes
Uses for Marine Plants• Seagrasses are used to filter sewage, in the
production of paper, for fertilizer, and their rhizomes can be eaten.
• Seaweeds can be eaten, are used in medicine, are a source of methane for fuel, are used in fertilizers, ice cream, chocolate milk, shampoo, lipstick, agar for bacterial growth, laminaria is a cervix dilater.
• Marine plants are important to their own environment because of their productivity, they prevent the removal of substrate, they filter water and provide habitat for animals.
Modes of Feeding
• Deposit Feeders: feed on detritus that has settled on the bottom. e.g. sea cucumbers
• Suspension Feeders: feed on plankton or detritus suspended in the water. e.g. barnacles, sponges, mussels, clams
• Grazers: herbivores (eat seaweed) e.g. limpets, abalone, sea urchins
• Predators: e.g. fish, nudibranchs, octopus• Scavengers: feed on dead organic matter, detritus
and larger leftovers, e.g. crabs, isopods
Modes of Feeding
Sea urchingrazer
BarnacleSuspension feeder
Crabscavenger
Sea cucumberDeposit feeder
Modes of Reproduction• Fission: Splitting in half, forming 2 clones of equal size,
asexual, e.g. sea anemone• Budding: small growths the “break off” and become
individuals, asexual, e.g. sponges• Spawning: release gametes into water, more offspring, but
less survival e.g. mussels, sea urchins, some fish• Internal fertilization: sperm transfer to female, e.g. snails,
squid, octopus, sharks• Hermaphroditism: an individual is both male and female
e.g. sea anemone, sea slugs (nudibranch)• Egg Laying: can occur before or after fertilization• Sex Changes: Some fish, anemone, slipper snail• Brooding: parental care, fewer offspring but greater
survival, e.g. slipper snails, anemone, some sea stars, some fish
Rocky Shores• The “Intertidal Zone” is the shore
area between the highest and lowest tides.
• To live in a Rocky Shore organisms must have adaptations that allow them to prevent:
1) Removal from the substrate by waves (e.g. byssal threads in mussels, holdfasts in algae)
2) Physical Damage from Waves (e.g. limpets have thick, low profile shells and dig pits in the rocks)
3) Dessication (run and hide or “clam up”)
4) Temperature extreme fatality5) Salinity change fatality
p. 217-222
Rocky Shore• Rocky Shores are heavily
populated, and the limiting resource is not food, but Space. Food is abundant, but space is limited. There is great competition for space, so dispersal and quick colonization is important. Often plants and animals attach to other plants and animals.
• The Rocky Shore is characterized by great diversity, but low abundance.
p.223-225
Vertical Zonation of Rocky Shore• Each creature living in the
Rocky Shore has a different tolerance for emersion and immersion and are therefore only found within a particular vertical range, resulting in a banding pattern called vertical zonation. These zones are very obvious on steep slopes and less so on gradual slopes.
p.225-226, 230
Vertical Zonation of Rocky Shore• The upper limit of a zone for a creature is set by physical
factors (emersion time, wave action) e.g. if there is gentle wave action, rocks will have more algae. If there is heavy wave action, rocks will have more barnacles, mussels and limpets.
• The lower limit of a zone for a creature is set by biological factors (competition, predation)
• E.g. Keystone Predator: a predator that is important in maintaining the structure of the community …in a rocky shore sea stars are a keystone predator that limits the mussel zone.
Upper Intertidal Zone• Seldom under water…”Splash zone”
• Green algae, lichen, periwinkle snails, limpets
p.226-233
Middle Intertidal Zone• Regularly uncovered and covered with water
• Acorn barnacles, mussels, rockweed (brown)
Lower Intertidal Zone• Covered by water most of the time• Dominated by seaweeds of all types and many small
creatures• Laminaria, Egregia, sea anemones, small fish, Sea
slugs
Sandy Shore• Soft bottoms are unstable and shift in response to waves,
tides and currents. So organisms do not have solid places to attach.
• Few primary producers live here and the water motion is great, so the main food is suspended in the water: plankton and detritus.
• Burrowers and suspension feeders: clams, sand crabs, polychaete worms,
• Predators: sea birds, surf perch, swimming crab• Upper beach: amphipods, isopods• The Sandy Shore has low diversity, but great abundance.
p.234-239
Salt Marsh or Estuary
• Fresh water rivers and salt water tides meet here.
• Consists of mud flats and grass marshes• The margins are dominated by grasses:
Cordgrass & Pickleweed• Mudflats have much bacteria, worms, crabs,
snails, fish, sea birds• Estuaries are fish nurseries for many species
Subtidal Soft Bottom• The sandy/muddy bottom which is always underwater and on the
continental shelf• Low diversity but great abundance• Epifauna live on the sand, Infauna live in the sand• Closer to shore is sand and suspension feeders; farther from shore
are finer muds and deposit feeders.• Detritus is the main food.• Large populations of deposit feeders: worms, heart urchins, sand
dollars, brittle stars, sea cucumbers• Suspension feeders: many species of clams• Predators: moon snails, sea stars, crabs, octopus, rays and skates,
halibut, angel shark, gray whale
p.260-266
Kelp Forest
• Restricted to cold water with much water movement over rocky bottoms.
• Kelp can grow 20 inches per day• Layers include the canopy, understory and
bottom… all of which have great diversity of species
• Kelp grazers: sea urchins, abalone, sea hares• Fish: Sheephead, rockfish, • Keystone species: sea otter, sea urchin, kelp
p.270-274
Coral Reef Types• Fringing Reef: develops close to shore• Barrier Reef: develops far from shore with a lagoon in
between as volcano subsides• Atoll: a ring around a central lagoon after volcano has
sunk.
p.284-290
Corals• Corals are like miniature sea
anemones that grow in colonies and make the rock they live in, building cup-like holes
• Individuals are called polyps.• Most contain zooxanthellae
algae in a symbiotic relationship where the coral provide a home while the algae provides food by photosynthesis. Coral also eat.
p.276-280
Coral Reef Residents• The organisms that make up the main
structure of a coral reef are stony corals, soft corals and sponges
• Coral reefs need intense light and warm temperatures p.280-283,
292-298