Key to Invertebrates Found At or Near

The Rosario Beach Marine Laboratory

(a campus of Walla Walla University)

Fidalgo Island, Anacortes, WA

Anthopleura elegantissima anemone dividing

This page serves as an entrance to a fascinating look at many of the marine invertebrates found in Puget Sound and the Straits of Juan de Fuca, Washington. Each species has a special page with its description and notes about its natural history, plus observations we have made of the species. Most of the photos were taken of live animals, either in the field or in the lab on animals that were then returned to the field. I am a scientist and teacher, not a professional taxonomist and I have been known to mis-identify a species on occasion, so if you see something that needs to be corrected please contact me. My sincere thanks to the experts on various groups who have given me advice and helped with identification. You can also check out my main web page at http://people.wallawalla.edu/~david.cowles

If you know the taxonomy of your species you may quickly navigate directly to it; otherwise you may use the dichotomous keys to find out what it is. Wherever possible, the keys are supplemented with definitions to terms and with pictures of relevant species and the parts being compared.

Alphabetic List of Species and Groups

Illustrated Glossary

Systematic Index
(Organized in Systematic order, alphabetically under phyla)
Annotated Bibliography

Key to Species--Starting with Recognizable Group

(Starts with Phylum, Class, or other recognizable group, which are listed alphabetically by phylum)

Other Web Resources

Key to Groups of Invertebrates
(Start here if you don't know what kind of animal it is or what group an animal is in)

Instructions on how to use a dichotomous key
Send me Feedback
(comments, corrections, observations, permission to use photos)

This key is a long-term project edited, coordinated, and maintained by Dave Cowles. I am grateful for the many students I have had opportunity to work with over the years, some of which have contributed directly to this key. The names of student authors and editors are listed at the bottom of the pages they worked on in some way, and in the list of contributors.
Some frequently-used names, like my own, may be abbreviated. Click here for a list of abbreviated names.

The key currently contains more than 351 species in 17 Phyla, 76 Orders, and 84 Families.

Keys to Species, Starting By Recognizable Group (Arranged Alphabetically by Phylum):

In the list below, just click on the taxonomic level that you wish to jump directly to. Phyla are listed in alphabetic order.
Phylum Annelida: Segmented worms
Class Polychaeta

Phylum Arthropoda: Crustaceans and Chelicerates
    Subphylum Chelicerata
        Class Pycnogonida: Pycnogonids, sea spiders
    Subphylum Crustacea
        Class Maxillopoda
           Infraclass Cirripedia: Barnacles
        Class Malacostraca
            Superorder Eucarida
                Order Decapoda
              Infraorder Thalassinidea: Mud shrimp and ghost shrimp
                    Infraorder Anomura: Hermit crabs and other crablike species
              Infraorder Brachyura: True crabs
           Natantia--shrimp (Caridea) and prawns (Dendrobranchiata, Penaeida)
              Infraorder Caridea: Shrimp
              Infraorder Penaeidea: Prawns
            Superorder Peracarida
           Order Amphipoda: Amphipods
           Order Isopoda: Isopods
           Order Lophogastrida: Lophogastrids--Deep-sea shrimplike species such as Gnathophausia

Phylum Brachiopoda: Lampshells

Phylum Bryozoa

Phylum Chordata
Subphylum Urochordata: Tunicates, salps, doliolids, larvaceans
Class Ascidiacea: Tunicates, sea squirts

Phylum Cnidaria:
    Class Anthozoa: Anemones, corals, sea pens
    Class Hydrozoa: Hydroids, siphonophores, hydrozoan jellyfish
        Hydromedusae
        Hydroid polyps (Order Hydroida have a well-developed polyp--most colonial hydroids are here)
        Orders Chondrophora/ Siphonophora (Siphonophores--pelagic, floating or midwater colonies with float or swimming bells)
        (sub)order Stylasterina (fire corals and their relatives)
    Class Scyphozoa: True jellyfish
        Order Semaestomae: Pelagic jellyfish
        Order Stauromedusae: Attached jellyfish

Phylum Ctenophora: Comb jellies

Phylum Echinodermata
    Class Asteroidea: Sea stars
    Class Echinoidea: Urchins and sand dollars
    Class Holothuroidea: Sea cucumbers
    Class Ophiuroidea: Brittle stars, basket stars

Phylum Echiura: Echiuroid worms, spoonworms

Phylum Entoprocta: Entoprocts

Phylum Hemichordata: Hemichordates
Class Enteropneusta: Acorn worms

Phylum Mollusca:
    Class Bivalvia: Bivalves: Clams, mussels, scallops
    Class Cephalopoda: Octopus and squid
    Class Gastropoda: Snails and nudibranchs
        Subclass Prosobranchia: Most marine snails with shells
        Subclass Opisthobranchia: Nudibranchs, etc.
    Class Polyplacophora: Chitons
    Class Scaphopoda: Tusk shells

Phylum Nemertea: Ribbon or proboscis worms

Phylum Platyhelminthes: Flatworms
Class Turbellaria: Freeliving flatworms

Phylum Porifera: Sponges
Class Demospongiae (Most of our common sponges are here)

Phylum Sipuncula: Peanut Worms

How to Use a Dichotomous Key:

A Dichotomous key is a simple pathway to find specific information, based on a simple principle. Choices in the key are numbered consecutively. Each choice gives you only two options about your species, and you must decide which of the two options matches your species. For example, choice 1a may say the species is spherical while choice 1b says the species is not spherical. If your species is shaped like a cube, you would choose choice 1b. At the right of each choice is a number to jump to next if that choice is correct. For example, if choice 1b had a "7" beside it, that would mean to go next to choice 7 if choice 1b is correct. You continue this process until you arrive at the correct species.

This key has some real advantages over a normal printed key. First, it is web-based, and each choice is a link. That means you can quickly travel through the key, and even back up (by using your browser's back button) easily. Just click on the number after the correct choice and you will be taken to the next choice. It also has many definitions and illustrations throughout, so that you can easily see what terms mean or see special structures that are described.

Click here or use your browser's back button to return to the top of the page

Page created by Dave Cowles, 6-2002
Edited by: Anna Dyer, 08-2002
Edited by: Melissa McFadden, 08-2002
Edited by: Dave Cowles, 2003, 2004, 2005, 2006

Alphabetic List of Species and Groups		Illustrated Glossary
Systematic Index (Organized in Systematic order, alphabetically under phyla)		Annotated Bibliography
Key to Species--Starting with Recognizable Group (Starts with Phylum, Class, or other recognizable group, which are listed alphabetically by phylum)		Other Web Resources
Key to Groups of Invertebrates (Start here if you don't know what kind of animal it is or what group an animal is in)
Instructions on how to use a dichotomous key		Send me Feedback (comments, corrections, observations, permission to use photos)