Horse Bot Fly


Domain:  Eukarya
Kingdom:  Animalia
Phylum:  Arthropoda
Class:  Insecta
Order:  Diptera
Family:  Oestridae
Genus:  Gasterophilus
Species:  Gasterophilus intestinalis

Domain: Eukarya
Eukarya includes all organisms with a true nucleus. A nucleus contains genetic material that controls the cell. They also have membrane-bound organelles that carry out specialized functions for the cell.

Kingdom: Animalia
Animalia includes heterotrophic organisms. They are unable to produce their own food like plants, so they must consume other organisms. They are multicellular and motile.

Phylum: Arthropoda
A synapomorphy for Arthropods is a jointed exoskeleton of chitin that they shed as they grow. It is separated into a head, thorax and abdominal region. An exoskeleton serves as protection against predators and as a support structure for internal tissues. Joints allow for better movement. To learn more about the phylum Arthropoda click here.

Class: Insecta
Hexapoda refers to insecta, meaning split up into segments (Biology, 1997). These organisms have three pairs of limbs, three body regions, wings, antennae, and compound eyes (Bug Guide, 2003).

Order: Diptera
Diptera includes flies that have a pair, or two wings, total. Most have compound eyes and an antennae (Resh and Cardé, 2003).

Family: Oestridae
Oestridae include parasitic fly larvae that develop in their host (Featured Creatures, 1996).

Genus & Species: Gasterophilus intestinalis
Gasterophilus refers to the common host the organism infects, which is the horse. Gasterophilus intestinalis refers to the location the organism infects in the host, which is the digestive tract (Featured Creatures, 1996).


Phylogenetic Trees:

Made by Courtney Swanson 2014Gasterophilus intestinalis is similar to its relatives in the phylum Arhtropoda in that, as stated above, Arthropods are know for their exoskeleton separated into various regions. It shares a common ancestor with organisms in Arachnida, Malacostraca and many other classes within Arthropoda. Arachnida includes spiders, such as the Sydney Funnel-Web Spider.  These organisms differ from the Insecta in that they have more legs and less body regions. Malacostraca includes crayfish and crabs, such as the Yeti Crab.  These organisms also differ from Insecta in that they have more legs and less body regions. Insecta is the largest reservoir of organisms. Many organisms have still yet to be discovered (Biology, 1997).


Figure 1. Phylogenetic tree of Gasterophilus intestinalis that includes domain, kindgom, phylum, class and respective relatives.


The order Diptera is within the class Insecta, and Diptera organisms share a common ancestor with organisms in the orders Orthoptera, Isoptera, Lepidoptera and Hymenoptera. Orthoptera and Isoptera both differ from Diptera in that these organisms’ wings grow outside of an encasement. Orthoptera include grasshoppers like the Short-horned Grasshopper, while Isoptera include termites. Lepidoptera and Hymenoptera are similar to DiptMade by Courtney Swanson 2014era in that these organisms’ wings grow inside of an encasement until they morph into an adult stage. Lepidoptera include butterflies like the Eastern Swallowtail Butterfly, while Hymenoptera include bees and ants like the Black Carpenter Ant (Biology, 1997). Families within the order Diptera are classified by how they acquire nutrition. The family Culicidae includes mosquitoes, whose source of energy is blood that they acquire through biting. Horse flies in the family Tabanidae also bite. The family Tephritidae includes fruit flies, whose source of energy is plant tissue. Other families within the order Diptera include decomposers and those that prey on organisms within the class Hexapoda. Gasterophilus intestinalis, however, is within the parasitic family Oestridae (General Entomology, 2013). Another parasitic fly is the Warble Fly.

                                             Figure 2. Phylogenetic tree of Gasterophilus intestinalis that inclues class, order, family and respective relatives.

Now that you know classification, let's take a look at the horse bot fly's habitat!

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