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harvestmen

Opiliones

What do they look like?

Harvestmen have small round bodies with eight very long, very thin legs. Like ticks and mites, harvestmen have evolved a tight connection between the two body sections that other Arachnids have. Their whole body is one round unit. On either side of their mouth they have short appendages called pedipalps that they use to hold food while they chew it.

Where do they live?

These long-legged arachnids are found all around the world. They are most diverse in tropical Southeast Asia and South America, but there are harvestman species everywhere, even in much colder regions.

What kind of habitat do they need?

Harvestmen need humid places to live. They are most often found in forests and caves, climbing on rocks and vegetation.

How do they grow?

These animals have to shed their exoskeleton in order to grow. They don't change their shape much as they grow, just get bigger and grow longer legs. Often they hang upside down while shedding.

How long do they live?

Usually only one year.

How do they behave?

Not much is known about the behavior of this group. Some are active at night, some in daylight.

How do they communicate with each other?

Harvestmen have eyes, but don't see very well. They probably rely on touch and smell

What do they eat?

Harvestmen eat very small invertebrates, and scavenge on larger dead ones and dead plant material.

  • Primary Diet
  • carnivore
    • eats non-insect arthropods

What eats them and how do they avoid being eaten?

These animals have large glands that produce toxic chemicals to keep predators away. They also can shed their legs, and move fast even if they loose a couple. If a predator grabs a leg, the harvestman will just leave it behind, still twitching and distracting the predator, while the rest of the animal gets away.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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Neotropical

living in the southern part of the New World. In other words, Central and South America.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.

carnivore

an animal that mainly eats meat

chaparral

mid-altitude coastal areas with mild, rainy winters and long, dry summers. Dominant plant types are dense, evergreen shrubs.

crepuscular

active at dawn and dusk

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

nomadic

generally wanders from place to place, usually within a well-defined range.

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

parthenogenic

development takes place in an unfertilized egg

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Climbing plants are also abundant. There is plenty of moisture and rain, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

solitary

lives alone

taiga

this biome is characterized by large expanses of coniferous forest, there is an extended cold season and heavy snowfall.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

 
University of Michigan Museum of ZoologyNational Science Foundation

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. "Opiliones" (On-line), Animal Diversity Web. Accessed April 21, 2014 at http://www.biokids.umich.edu/accounts/Opiliones/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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