Halacaridae:  Marine mites

Common name(s): 

Synonyms:  Marine mite
Phylum Arthropoda 
Subphylum Chelicerata
Class Arachnida
Superorder Acariformes
Order Trombidiformes
Suborder Prostigmata
A marine mite of Family Halacaridae.  Total length about 1/2 mm.  Many diatoms and other debris are adhered to the legs.  This individual was crawling around on a subtidal barnacle.
(Photo by:  Dave Cowles, August 2008 )
Description:   Marine mites are chelicerates related to spiders (but in a separate Order).  They are in the same Order as ticks and chiggers.  Their body is divided into sections, an anterior prosoma (similar to a cephalothorax) and a posterior opisthosoma (similar to an abdomen).  These two sections are often fused together in mites.  Mites are usually small, and are very diverse.  Size of individuals in this family ranges from 0.18 to 2 mm long.

How to Distinguish from Similar Species:  The "velvet mite" Neomulgus littoralis is a commonly encountered species found in the high intertidal and supralittoral.  It is bright red and may reach 3-4 mm long. Thinoseius orchestoidae is a member of Suborder Mesostigmata.  It attaches to the undersides of the beachhoppers Traskorchestia and Megalorchestia and preys upon nematodes that also live on the amphipods.  Members of Suborder Astigmata are mostly small, weakly sclerotized forms that are often found around green algae in tide pools.  Suborder Orbatida are dark, heavily sclerotized mites that are often herbivorous and found in the upper intertidal.

Geographical Range:

Depth Range:  Members of this family live from intertidal down to at least 5000 m depth.

Habitat:  Members of the family live in many different habtats, though individual species tend to be habitat-specific.

Biology/Natural History:   Some marine mites are phytophagous (suck from plants/algae), some are predators, and some are parasites.  The shape and habits of this individual suggest that it is a predator.

Halacaridae use spermatophores during reproduction.  One of their larval stages has only 6 legs instead of 8.  The larval stages are followed by one to several nymphal instars before they become adults.  At least 14 genera of Halacaridae are found in the Pacific Northwest.

Unlike the few insects and spiders which may be found in marine habitats but must breathe air, mites are able to absorb oxygen from the water so they can live at great depths.



Dichotomous Keys:
  Carlton, 2007 (Most information is here)
  Kozloff, 1987, 1996
  Smith and Carlton, 1975

General References:
  Morris et al., 1980

Scientific Articles:
Bartsch, I., 2004.  Geographical and ecological distribution of marine halacarid genera and species.  Experimental and Applied Acarology 34: 37-58

Kitron, U. D., 1980.  The pattern of infestation of the beach-hopper amphpod Orchestoidea corniculata, by a parasitic mite,  Parasitology 81: 235-249

Krantz, G. W., 1973.  Four new predatory species of Halacaridae (Acari: Prostigmata) from Oregon with remarks on their distribution in the intertidal mussel habitat (Pelecypoda: Mytilidae).  Annals. Entomological Society of America 66: 979-985

Krantz, G. W., 1976.  Arenicolous Halacaridae from the intertidal zone of Schooner Creek, Oregon (Acari: Prostigmata).  Acarologia 18: 241-258

McQuitty, M., 1984.  The marine Halacaroidea from California.  Journal of Natural History 18: 527-554

Rigby, M. C., 1996.  The epibionts of beach hoppers (Crustacea: Talitridae) of the North American Pacific coast.  Journal of Natural History 30: 1329-1336

Web sites:

General Notes and Observations:  Locations, abundances, unusual behaviors:

Authors and Editors of Page:
Dave Cowles (2008):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)