Everything Earthworms

I'm Diggin' It

Objectives

1) Study and dissect an earthworm and become familiar with internal and external anatomy

2) Focus on the organs, structures, and functions of the digestive system

Background Information

Scientific Name: Lubricus Terestris

Habitat: underground

Predator: birds, lizards, moles

Food: soil, dirt

Adaptations: streamlined body aids in movement; hermaphroditic; breathing through a mucus coating

Dissection!

Worm Cladogram

System Focus:

Throw Your Pharynx in the Air Like You Just Don't Care

Earthworms eat by passing soil through their digestive system and extracting the edible material. Worms expel their pharynx through their mouth opening, and then suck their pharynx back into their body to digest. Food passes through the mouth into pharynx, down the esophagus, and into the crop which temporarily hold food until the gizzard has more free capacity. The gizzard acts like a mouth and grinds the edible material into tiny pieces and send it to the intestine. The intestine soaks up all of the nutrients into the worm's bloodstream. The left over material is waste and expelled through the anus.


The digestive system of a worm maintains homeostasis for the rest of the body. However, apart from sustaining the body, the digestive system doesn't really work closely with any other systems.

Cross Content:

Human Impact

We don't eat earthworms in the US, so they aren't benefiting us by providing food. However, they are improving the soil aeration, porosity, and permeability by tunneling through. They also decompose dead organisms, and the mass amount of earthworms makes them a good source of bait for fishers.

Taxonomy

The earthworm belongs in the Lumbricus species, which is an assorted species including the Lumbricus Terrestris and Lumbricus Rubellus. Categorization of the earthworm into one of it's taxonomic families is based on a few features, like the makeup of the clitellum, the location and disposition of the sex features, number of gizzards, and body shape. Currently, over 6,000 species of terrestrial earthworms are named.

Evolution

Earthworms, like all annelid worms, regularly segmented. Not only is the body of the worm divided into a series of segments, but those segments are shown in repetition, so that each segment is alike to the next. Because of this, each segment has mostly its own muscle systems, nerve center, excretory organs (nephridia), ceolom, and segmented blood vessels.

Researchers have suggested that segmented worms evolved when chains of worms did not separate correctly, or that the genetic code may have repeated its design several times over to produce a worm as such.

Interesting Information

  • Worms are coaxed into coming up to the surface by raindrops beacus they don't want to get suffocated by the damp soil. This is also why birds peck at the ground (to make the words think it is raining.)
  • they can be found on every continent, except Antartica
  • they are hermaphrodites (seminal vesicles and seminal receptacles)
  • baby worms are hatched from cocoons that are smaller than a grain of rice

Punny Earthworm Jokes

What did the worm say to the other when he was late home?

>Where in earth have you been?


Why did the worm have 5 lovers?

>It had 5 hearts.

The Adventures of Vermi the Wormy

Biography

By

Maya Waterland

Guzman - PAP Bio - 7