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Northwest Wildlife Online
by John M. Regan
The Invertebrates
Protozoa Sponges Cnidarians Ctenophores Arthropods Echinoderms Mollusks Nematodes Flatworms Annelid Worms
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Talk about biting off more than you can chew! Invertebrate wildlife is a staggering subject; more than any single website can provide justice. I'm stretching things by trying to provide an overview of all the backboned wildlife in the Northwest. Throw in the creatures who do not sport that unique tube of calcium and we are in way over our head.
To begin with, let's talk numbers. Of the million plus currently described species of animals on earth only about 5 percent have a backbone of some kind. The rest - more than 950,000 species - are just fine without one, thank you very much. In fact, the only reason we divide the animal kingdom into vertebrates and invertebrates is our understandable bias toward backboned creatures. Most people would rather cuddle a puppy than an octopus.
Yet in terms of numbers, adaptability, morphology, physiology, survivability, color - and a host of other characteristics - the invertebrates have us beat hands (or no hands) down. From the fantastic conglomeration of microscopic, single celled organisms called protozoans to the 50 foot plus giant squid, the variety of non-backboned animals sharing our world is almost too incredible to comprehend.
Because the non-back boned animals of the world are so numerous, varied, and widespread, there are numerous, varied, and widespread ways to classify them. Trying to keep this confusion manageable, I've put together a major, and practical, list of Invertebrate Phyla:
Protozoa - Microscopic, single celled organisms; over 50,000 kinds with many as yet undiscovered
Sponges - Porifera are the most primitive of multicellular organisms. As you may surmise from the name they are, and look like, sponges. Very common in the Northwest they are mainly marine creatures, although some do inhabit freshwater.
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Cnidarians - These are the hydras, jellyfish, sea anemones, and corals. Many are brightly colored and exhibit radial symmetry.
Ctenophores - A relatively small phylum of about 90 species; these are the sea walnuts or comb jellies.
Arthropods - A truly gigantic phylum containing insects, spiders, crustaceans, and a host of lesser known animals all characterized by an external skeleton.
Echinoderms - Includes some of the most familiar marine species like sea stars, brittle stars, sea urchins, sand dollars and others, all characterized by an internal skeleton.
Mollusks - Some of our largest and most familiar invertebrates; includes octopus, squid, clams, oysters, snails, and slugs.
Nematodes - Also called roundworms, the nematodes are the most numerous multicellular animal in the world. Over 10,000 described species. Millions upon millions of these little guys live just about everywhere on the planet. Their numbers are truly staggering. According to one source more than 90,000 were recorded on a single decomposing apple! Many are parasitic.
Flatworms - Three Classes of worms; two of which are entirely parasitic. Includes the flukes and tapeworms.
Annelids Worms - Our familiar segmented worms such as earthworms. There are, however, a few surprises here. Follow the link for more.
Just from that incomplete list above you can see that we've got a ton of material to cover. But some of our invertebrates are so ubiquitous and so unique to this part of the globe it is inconceivable that any treatment of Northwest wildlife should omit them completely.
What makes the Northwest so invertebrate unique is the wonderful variety of ocean specimens so readily available, most visible right from the shore. Puget Sound may well be the starfish capital of the world with 30 different species. The Giant Plumose Anemone, largest in the world, is a common sight in any marina. Chitons and mussels cling to the boulders along the shore. The Giant Pacific Octopus, largest in the word, lives off shore, as does the Red Octopus and two species of squid, one of which is less than an inch long. With over 50 different kinds of shrimp and crabs we have crustacean chaos. Rocky shoals abound with a spectacular array of sponges, scallops, urchins, jellyfish, comb jellies, hydroids, anemones. Sand dollars by the ton can be unearthed less than an inch under our sandy beaches. Turn over the smallest rock in the ocean and dozens of Hermit Crabs scuttle for cover. The list goes on.
Snails, from microscopic to giants abound on land and in water, and if we aren't the slug capital of the world I'd like to who is. Our slugs range from almost hot dog size to less than half an inch with surprising variety of color. I've encountered three different species in my backyard and another four in the woods beyond. I'm sure there are more, and the species number alone does not tell the story of individual numbers, which must be staggering. Three different types of earth worms percolate our range drenched soil. Spider numbers are amazing. Enormous Black Carpenter Ants populate the forests (and some unfortunate homes). Horse Ants construct conspicuous mounds of thermo regulating pine needle nests. Dragonflies and Damselflies prowl the skies.
Obviously, I've only very lightly scratched the invertebrate surface. In weeks ahead the links below will take you to some of our more well known species. Invertebrate life is a fantastic study. Relatively easy to conduct and rife with potential for discovery it is a budding naturalist's prime opportunity for scientific contribution.
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Protozoans Sponges Cnidarians Ctenophores Arthropods Echinoderms Mollusks Nematodes Flatworms Annelid Worms
Birds Mammals Reptiles Amphibians Fish Invertebrates Home
Mission Editor Bio Contact Wildlife Park Links Further Study Wild Employment Northwest Trek