Marine Invertebrates
Chapter 7
The Classification of Organisms
Prokaryotes
Eukaryotes
Kingdom
Animalia
Kingdom
Protista
Domain Bacteria
Domain Archaea
Kingdom
Fungi
Kingdom
Plantae
Domain Eukarya
Animal Kingdom
• Characteristics of Animals:
– Eukaryotic
– Multicellular
– Heterotrophic
– Reproduce sexually
– Contain cells lacking a cell wall
– Usually capable of movement at some stage in life
Major Phyla of the Animal Kingdom
Phylum
Examples
Porifera
Sponges
Cnidaria
Jellyfish, sea anemones, corals
Ctenophora
Comb jellies
Platyhelmenthes
Flukes, tapeworms
Nematoda
Roundworms
Annelida
Polychaetes, leeches
Mollusca
Snails, clams, oysters, octopus, squid
Arthropoda
Crustaceans
Echinodermata
Sea stars, sea urchins
Chordata
vertebrates
Phylum Porifera
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Structurally simplest animal
Do not form true tissues or organs
Mostly sessile – living attached to a surface
Variety of shapes, sizes, and colors
Simple body plan
Filter feed on plankton
Reproduce sexually by broadcast spawning
Some reproduce asexually when buds break off
Sponge Anatomy
http://www.mun.ca/biology/scarr/Porifera.htm
Sponge Anatomy
Sponge Anatomy
Structure
Function
Pinacocyte
Flat cells covering the outer structure
Pore cells or porocytes
Tube-like cells that allow water to enter
Structure
Function
Choanocytes (or collar cells)
Cells lining the larger feeding chamber
of the sponge; contains a thin flagellum
to create a current and collar to trap
food particles
Oculum
Large opening on the top of the sponge
through which water exits the sponge
Structure
Function
Spicules
Used for structural support;
transparent siliceous or calcareous
structures of different shapes and sizes
(http://etc.usf.edu/clipart/47800/47878/47878_spo_spicules.htm)
Structure
Function
Spongin
Tough, elastic fibers to help support the
sponge
Can be sole means of support or found
with spicules
(http://www.palaeos.com/Invertebrates/Lists/Images/Spongin.jpg
Amebocytes
)
Wandering cells
Secrete the spicules and spongin
Can transport and store food particles
Some can transform themselves into
other types of cells
Sponge Feeding
• Suspensions feeders
– animals that eat
food particles
suspended in the
water
– Specifically, sponges
are filter feeders,
suspension feeders
that actively filter the
food particles
http://www.mesa.edu.au/friends/seashores/sponges1.html
Sponge filtering - http://www.youtube.com/watch?v=T7E1rq7zHLc
Sponge filtering http://www.youtube.com/watch?v=T7E1rq7zHLc
Sponge Reproduction
• Asexual (one parent) – when branches or buds
break off, they will grow into separate sponges
identical to the parent
• Sexual (two parents) – sponges produce sex
cells, gametes, nutrient rich eggs and sperm
with flagellum
– Broadcast spawning
Body Plans
• Sponges have three basic body plans:
– Asconoid
– Syconoid
– Leuconoid
Asconoid
• Simplest form
• A simple tube perforated by holes
• Central cavity, spongocoel, lined with choanocytes
http://animaldiversity.ummz.umich.edu/site/resources/klaus_jost/00017869.jpg/view.html
Syconoid
• Large tubular body with a single osculum
• Thicker body wall than asconoid
• Longer pores that that form simple canals
• Canals lined with choanocytes (not central
spongocoel)
http://animaldiversity.ummz.umich.edu/site/resources/Grzimek_inverts/Hexactinellida/Euplectella_aspergillum.jpg/view.html
http://eastchestereagles.wikispaces.com/Animal+Phyla+Even+Porifera
Leuconoid
• Most complex body plan
• Vast network of interconnecting canals that
eventually lead to one or numerous larger
oscula
<http://animaldiversity.ummz.umich.edu/site/resources/klaus_jost/00000222.jpg/view.html>
http://eastchestereagles.wikispaces.com/Animal+Phyla+Even+Porifera
Classes of Porifera
• Three classes of Porifera:
– Calcarea
– Hexactinellida
– Demospongiae
Classes of Porifera
• Class Calcarea
– includes sponges with all three body plans
– produce large spicules (megascleres) of calcium
carbonate.
• Classes Hexactinellida
– only possess leuconoid members
– produce six-pointed large and small spicules (megaand microcleres) made of silica.
• Class Demospongiae
– only possess leuconoid members
– may have microscleres and megascleres, spongin,
both, or neither