Chelicerata

General
The Chelicerata are a large and very diverse group of the arthropods. Among its many members are the spiders, mites, ticks, scorpions, harvestmen, pseudoscorpions, horseshoe crabs, and other less well known groups.  The Chelicerata are one of the four great living subdivisions of the Arthopods. The fifth major subdivision of the Chelicerata, the Trilobites, went extinct in the Permian at the end of the Paleozoic. These four subdivisions are: Crustacea, Chelicerata, Insecta, and Myriapoda. The Chelicerata, in turn, have three major subdivisions: the Pycnogonida (Sea Spiders), Xiphosura (Horseshoe Crabs), and the largest group the Arachnida (spiders, mites, ticks, scorpions, etc.).

GENERAL

Introduction to the Cheliceramorpha. University of California Museum of Paleontology, Berkeley. A short introduction to the Chelicerata with photographs and some information on biology, life history, morphology, systematics, and the fossil record.

 

PYCNOGONIDA (SEA SPIDERS)

The sea spiders are a fascinating group of marine animals most commonly associated with the ocean floor. Although they resemble spiders, they are not closely related and are sometimes assigned to a class separate from the Chelicerata.

Introduction to the Pycnogonida. Museum of Paleontology, University of California at Berkeley. This site offers a short introduction to the sea spiders with a photograph of a fossil species.

Animal Diversity Web. University of Michigan Museum of Natural History. A short introduction to the sea spiders.

Keys to Marine Invertebrates of the Woods Hole Region. Marine Biological Laboratory. A short introduction to the Pycnogonida with a key to the species found in the Woods Hole region of Massachusetts.

Underrekke Pycnogonida. This site is written in Norwegian, but it has a great photograph of a sea spider.

 

XIPHOSURA (HORSESHOE CRAB)

The Horshoe Crab is a living relict most closely related to the Eurypterids which flourished in the Silurian of the Paleozoic and went extinct during the Devonian. These strange animals with the flattened carapace and elongate tail (telson) live on the muddy ocean bottom and are commonly seen along the Atlantic Coast of North America, sometimes in great numbers.

Horseshoe Crabs. The Ancient Mariners. Beach-Net. This site has a photograph and information on the Horseshoe Crab.

The Assateague Naturalist. Photographs and information on the Horseshoe Crab.

The Horseshoe Crab. Patty Sturtervant. Information on Horseshoe Crabs.

Horseshoe Crabs. Photographs and information on Horseshoe Crabs.

 

ARACHNIDA

The Arachnida contain the largest and most diverse collection of groups in the Chelicerata and include the spiders, mites, ticks, scorpions, and other less well known groups. The spiders have their own page, but the other groups are listed below.

 

GENERAL

Onalaska High School. A short introduction to some of the groups of the Arachnida including the Opiliones (Daddy-long-legs), spiders, Amblypigida (tailess whip scorpions), and Palpigradi (microwhip scorpions).

 

ACARI (Mites and Ticks)

Gordon's Wonderful World of Insects. A short introduction to the Acari with links to other sites.

Tree of Life - Acari. D. Evans, J. Krantz, and E. Lindquist. A classification of the Acari with basic systematic information, an introduction to the Acari, and some references.

Tick Research Laboratory. University of Rhode Island. A great site with information on ticks and the diseases they carry. A large gallery of tick figures may be found here and links to other tick related web sites. You can also find the telephone number for the Lyme Disease Hot Line.

Images and Movies of Ticks. Iowa State University. Photographs and movies of ticks.

Mites.pdf - Pluchino, E. S. 1984. Guide to the common water mite genera of Florida. You will need an Adobe Acrobat (pdf) reader to view this document.

 

PSEUDOSCORPIONES (Pseudoscorpions)

Pseudoscorpions. Ohio State University Extension Factsheet. Information and figures of pseudoscorpions.

Pseudoscorpion. Hamilton University. An electron microscope picture of a pseudoscorpion.

 

SCORPIONES (Scorpions)

  Scorpion Emporium. Scott Stockwell. This is the ultimate scorpion site with photographs and information on biology, morphology, identification, systematics, and phylogeny. You can also find information about scorpion stings and links to other scorpion sites. Photographs of vinegaroons, whip scorpions, amblypigids, and solpugids along with some information on these groups can also be found here.

The Scorpion Fauna of California. Warren Savary. A checklist of the scorpions of California along with an identification key and bibliography.

 

SOLIFUGAE (Solpugids)

Bibliography for the Arachnid Order Solifugae. Warren Savary. A bibliography of references on solpugids in two parts is included at this site along with a checklist of the North American species.

Sun Spider Movies. Scott Stockwell. This site contains two Quick Time movies of a solpugid. The files are large and you will need Quick Time installed to the view the movies.

 

THELYPHONIDA (Whip Scorpions)

Whip Scorpion - BioByte Archives. A short description of whip scorpions.