This document compares and contrasts the characteristics of sponges and cnidarians. Sponges and cnidarians are both aquatic invertebrate phyla that reproduce both sexually and asexually. However, sponges lack tissues, organs and organ systems like the nervous, digestive and circulatory systems that cnidarians possess. Cnidarians also have a radial symmetry and can reproduce through both polyp and medusa life stages using external fertilization.

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Biology class
May 10th, 2012

2. Characteristics Sponges Cnidarians
Phylum Porifera Cnidaria
Animal x x
Invertebrates x x
Species 5,000+ 9,000+
Symmetry Assymetrical Radial
Aquatic (marine and freshwater) x x
Movement Sessile (adult) / free swimmers Sessile (adult) / free
(larvae) swimmers (larvae, adult)
Variety of colors, shapes and x x
sizes
Sexual and asexual reproduction x x
Layers 2 layers Endoderm / ectoderm
(embryonic stage)
Has no… Tissues > organs > organ system: Central nervous system (does
Nervous, digestive, muscular or have a nerve net)
circulatory systems.
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3. * Sponges * Cnidarians
Scyphozoa (jellyfish)
Anthozoa (corals
and sea anemone) Hydrozoa (hydra)
Cubozoa (box
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jellyfish)

4. * Sponges * Cnidarians
Epithelial-
like cells
Pore cells Polyp
Amoebocytes
Collar cells
Medusa
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5. * Sponges * Cnidarians
* Asexually – fragmentation, budding * Asexually – budding. Polyp or
or formation of gemmule. medusa stage.
* Sexually – Hermaphrodite. Internal * Sexually – one phase of the life
/ external fertilization cycle. Polyp (if no medusa stage
occurs) or medusa stage. External
fertilization.
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6. * Sponge * Cnidarians
* No digestive system * Prey captured by
* Filter feeding nematocyst brought to the
mouth by contraction of
tentacles and then to the
gastrovascular cavity.
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7. * Sponge * Sponge
* No nervous system * No nervous system
* Nerve net
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