Ranging from 0.25-10mm in length, there are typically around 10,000 per square metre of soil, rising to as many as 200,000 per square metre in some places. The 6,000 known species of these wingless arthropods can be found in all manner of habitats all over the world, from beaches and cliffs to the Antarctic and the highest mountain ranges on Earth.
Social workers provide counseling/therapy at mental health centers. There are several kinds of therapy including individual therapy, family therapy, home based family therapy, behavior therapy, or group therapy.
Increasingly, they also provide post-adoption counseling to help older adoptees deal with issues of self-identity, loss and self esteem as well as medical problems that may have a genetic component. Social workers provide a wide gamut of services in the foster-care system as well. These services are critical as the number of children in foster care continues to rise. In this arena, social workers assess at risk families to determine if a child needs placement.