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Zoology Preliminary Animal Worksheet
Typed, Upload to Turnitin.com. Put copy in section C of notebook. Due before class, on the day that we start observing the assigned animal.
Common name of animal: Earthworm
Phylogeny (classification and Scientific name)
Kingdom: Animalia (ITIS Report)
Phylum: Annelida (ITIS Report)
Class: Clitellata (ITIS Report)
Order: Opisthopora (ITIS Report)
Family: Lumbricidae (ITIS Report)
Genus: Lumbricus (ITIS Report)
species: terrestris (ITIS Report)
Why is this organism a member of this phylum?
Earthworms are a member of the phylum Annelida, which is comprised of earthworms, polychaete worms, and leeches. All of the members of the phylum are segmented. (Myers, 2001)
Why is this organism a member of this class?
Earthworms are a member of the class Clitellata, which is made up of segmented worms characterized by the clitellum, which is the bulge near the first third of the body. The clitellum plays a role in reproduction. (Ruppert, Fox, & Barnes, 2004)
- What type of symmetry:
Earthworms, as a member of the phylum Annelida, have bilateral symmetry (Levinton, 2008).
- How many germ layers:
Earthworms, as a member of the phylum Annelida, have three germ layers (Levinton, 2008).
- Types and names of body cavity(ies) if any.
Earthworms have a coelom. (Myers, 2001)
- Type of segmentation and number and name of segments. This may not be applicable to all animals.
Earthworms have segmentation and are made of about 100-150 segments (Earthworms) These segments, calling “annuli”, are covered in setae. These help the worm move and burrow (Sartore, 2018).
- Type of support/locomotion system.
The segmentation of the worm’s body increases the efficiency of movement by allowing the muscle contractions have a stronger effect by localizing it. In addition, their body walls made of both circular and longitudinal muscle fibers that are surrounded by a moist, acellular cuticle secreted by an epidermal epithelium. Earthworms also have chitinous hair-like structures, called setae, that project from their cuticle (Meyers, 2001)
Describe the respiratory and circulatory systems
- Earthworms do not have lungs, but instead breathe through their skin through diffusion. Because of this, the skin needs to be kept moist. This is achieved through the production of body fluid and mucus, as well as the earthworm’s habitat of damp or moist soil (Earthworms).
- Earthworms have a closed and segmentally-arranged circulatory system (Myers, 2001). There are three main groups of vessels: the aortic arches, dorsal blood vessels, and ventral blood vessels. The five pairs of aortic arches are the worm’s equivalent of a heart, as they pump blood into the dorsal and ventral blood vessels. The dorsal blood vessels carry blood to the front of the body, while the ventral blood vessels carry blood to the back of the body (Earthworms).
Describe the digestive and excretory systems.
- The digestive system of the worm is essentially a tube with a mouth and an anus (Myers, 2001). The digestive system consists of a pharynx, esophagus, crop, gizzard, and intestine. The worm first consumes food, such as soil, through the mouth, and the food then passes through the pharynx. From the pharynx, the food enters the esophagus, where calciferous glands release calcium carbonate to get rid of excess calcium. The food then passes into the crop, where it is stored until it goes to the gizzard. The gizzard contains stones that are used to grind food completely. The food then goes through the intestine, where gland cells release fluids to assist in digestion, and the walls of the intestines contain blood vessels that absorb and transport the food throughout the worm’s body. The food is then excreted through the worms anus. The excretions of the worms are called castings, which contain many nutrients that plants can use. (Earthworms)
Describe the type of nervous system
- earthworms have a segmented nervous system that consists of a pair of cephalic ganglia attached to double nerve cords, which run along the ventral body wall. The ganglia and branches are located in each segment (Myers, 2001). This causes sensory information and muscle control to be localized. The “brain” of the worm is located above the pharynx. There are touch, light, vibration, and chemical receptors along the worm’s body (Invertebrate Nervous System).
Describe reproduction and development
- Earthworms are hermaphrodites; however, they are not self-fertilizing. When they mate, they line up inverted to each other and exchange sperm. Each worm has two male openings, two sperm receptacles, and a pair of ovaries. The clitellum, the defining feature of this class, forms a slime tube that fills with albuminous fluid. The worm moves forward, out of the tube, and the tube then passes over the female pore and picks up eggs. As it continues to move down the earthworm, it passes over the male opening, called spermatheca, and is fertilized by the stored sperm. Once the eggs are fertilized, the slime tube closes off to form what is known as an “egg cocoon.” The eggs have a 2-4 week gestation period before hatching (Earthworms).
- What is this organism’s habitat?
Earthworms live in moist soil or mud. They are indigenous to Europe but are now easily found in North America and western Asia (Sartore, 2018)
- What type of special adaptations does it have for this habitat?
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