Download Chapter 6 Simple Marine Animals

Simple Marine Animals
Zooplankton in the Sea
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Plankton- organisms that float or drift on
the ocean surface
Include unicellular protists and
multicellular jelly fish
Plantlike plankton are phytoplankton
Animal-like plankton are zooplankton
Zooplankton Diversity
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Divided into two groups:
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1. Temporary zooplankton
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2. Permanent zooplankton
Temporary zooplankton
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The embryos or larvae of fish, crabs,
sponges, lobsters, clams and others
Spend early part of their life cycle floating
and drifting near the ocean’s surface
When they mature, they settle to the
bottom where they develop into adults (no
longer plankton at this point)
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Crab, sea star, barnacle & sea urchin larvae
Permanent Zooplankton
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Species that remain in the plankton
population throughout their entire life
cycle
Ex. Foraminiferans
Unicellular
Encased in a shell or test
Made of calcium carbonate (CaCO3)
Shell falls to the seafloor when they die
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Ex. Radiolarian
Transparent because its cell wall is made
of silica
Have long spines that help with buoyancy
& protection
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Ex. Copepod
Most numerous of all permanent
zooplankton
Shrimplike
Feeds on phytoplankton like diatoms
Important link in marine food chain
Protozoans
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Single celled Protists
Divided into:
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Ciliophora
Zoomastigina
Sarcodina
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Ex.Ciliophora
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Ex. Zoomastigina
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Largest group of protozoa
All have cilia
Animal-like
Move with flagella
Euglena & dinoflagellates
Ex. Sarcodina
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Move by cytoplasmic extensions called
pseudopods
Includes forams, radiolarians, and amoebas
Sponges
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Classified in Phylum Porifera
Benthic (bottom dwelling)
Multicellular animal with three layers:
1. Endoderm- inner layer of
undifferentiated cells
2. Ectoderm- outer layer of cells
3. Mesenchyme-jellylike material between
the endoderm and ectoderm
How does a sponge feed?
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Water enters the sponge through tiny pores
called Ostia
Water and wastes exit through the large hole,
called the osculum, located at the top of the
sponge
Collar cells inside the sponge have flagella and
produce the currents that move the water
Collar cells also trap and digest food
Benefits of sponges:
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1. Very efficient filters of the marine
environment (100 liters of seawater/hour)
2. Recycle minerals back into the water
Rotifers
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Multicellular
Phylum Rotifera
Live in moist sand along the shore
Draws in water through it’s mouth by cilia,
eats the floating food, passes through the
digestive tract and out the anus
Rotifer Reproduction
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External fertilization & development
Sexual- male sperm and female egg meets
up to form a zygote
Asexual- (parthenogenesis) female
produces one egg with two sets of DNA
which can develop into a female rotifer
Bryozoans
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Benthic organism mistaken for a sponge
Name means “moss animal”
Microscopic multicellular animal that lives
in a box shaped compartment
Branching colonies of these “boxes” of
bryozoans live together on rocks,
seaweeds, and shells