Hobo spider. Property of: Tobias Mercer


The hobo spider is found at about the middle of the food chain.  It feeds on mainly primary consumers, but there are many things that eat the hobo spider as well.  It is heterotrophic, meaning it has to consume otCommon House Fly. Property of: Joejhaldaher organisms to get its food.  It is specifically a carnivore because it doesn’t feed on plant material.  The hobo spider is successful at capturing food because it uses its web effectively.  It is a member of the family Agelenidae, which is composed of the funnel web weavers.  The web that these spiders spin is flat, layered, and has a funnel-shaped spot in the back.  The spider sits in this spot and waits for its prey to come.  Unlike some webs, the webs of funnel web weavers are not sticky.  The web trips up the insect when it flies by and then the spider attacks it with its fangs that are on the chelicerae.  The venom in the fangs kills the prey and then the spider releases digestive enzymes to digest it.  The spider then consumes it using its chelicerae.  It may wrap the prey in silk if it doesn’t feel like eating at the moment to preserve it for a later time.  The diet of Tegenaria agrestis is composed mainly of small insects.

Spider anatomy. Property of: John Henry Comstock

Once the hobo spider does consume its prey, it needs to distribute the nutrients out to the entire body.  Tegenaria agrestis does this effectively via a circulatory system, specifically an open circulatory system.  In an open circulatory system, the transfer fluid in the organism isn’t enclosed by veins or arteries.  The transport fluid is pumped from the heart and travels to other parts of the body via blood vessels, but once it gets to a certain spot it is released from the vessels.  The transport fluid then “bathes” that particular part of the body and gives it nutrients.  In humans the transport fluid is blood, but in spiders it is hemolymph.  Hemolymph is blood mixed with other kinds of fluids.Funnel web spider. Property of: RickP
The hobo spider also needs to oxygenate the hemolymph.  Humans have lungs to do this, but this is not the case for spiders.  They have a system in place called book lungs.  They are folded respiratory surfaces that almost look like the pages of a book.  The respiratory surfaces are an alternating stack of fluid compartments and air sacs.  These structures allow the hobo spider to breath and perform respiration.  They are found in the abdominal cavity of the spider.

Life of the Hobo