hydroids

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Hydroids have three stages in their life-cycle: a tiny free-swimming worm-like larva, which settles and grows into an attached animal, usually a branched colonial animal with individual hydroid polyps as shown here, which then releases jellyfish-looking medusae. Through evolution, many hydroids retain the medusa on the attached colony. Each individual hydroid polyp has a tubular body with a terminal mouth, surrounded by tentacles. The polyps are joined from their base to a common living tube running throughout the colony, which allows for food exchange of food among individuals. Reproductive polyps occur on the colony, releasing either worm-like larvae or medusae, depending on the species. Most hydroids inhabit marine environments.


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mastro26

Sea spider crawling on hydroid.

Sea spiders are also called pycnogonids and sometimes whip scorpions. Adult sea spiders either suck the juices from soft-bodied invertebrates, or browse on hydroids and bryozoans.


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mastro27

Identification assistance would be appreciated.

Text ©Peter Brueggeman. Photographs © Norbert Wu, Jim Mastro, & Canadian Museum of Nature (Kathleen Conlan). Photographs may not be used in any form without the express written permission of Norbert Wu, Jim Mastro, & Canadian Museum of Nature (Kathleen Conlan). Norbert Wu no longer grants permission for uncompensated use of his photos under any circumstances whatsoever; want more info?