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By Liviu, Ross, and Yuchen

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1 By Liviu, Ross, and Yuchen
Nematoda By Liviu, Ross, and Yuchen

2 Ross Overview Nematodes are slender worm-like animals that are usually microscopic, but can grow to as long as 2 inches, or even a meter, long. Their bodies will often have ridges, rings, warts, bristles, hooks, etc. The main difference between nematodes (roundworms) and all other worms is that these are NOT SEGMENTED.

3 Phylum & Sample Animals
Ross Phylum & Sample Animals Phylum: Nematoda Sample animals: Roundworms. That’s it. Metazoa: Animals with fixed body plan Eumatzoa: All animals but sponges Bilateria: Bilaterally Symmetric

4 Body Cavity and Symmetry
Yuchen Body Cavity and Symmetry Body Cavity - Nematodes have fake body cavities and thus are called Pseudocoelomate. The cavity is partially lined by tissue derived from the mesoderm. The other is separated by the digestive cavity that is not derived from the mesoderm. They are bilateral - if you cut them from the mouth you can only get one plane of symmetry. Think worms.

5 Circulatory and Nervous System
Yuchen Circulatory and Nervous System They DO NOT have a circulatory system ;_; They DO have an Nervous system which form an central ring near the anterior end of the nematode that forms a pseudo-brain. The rest is 4 nerve chords that run along the 4 sides (dorsal, ventral and laterals) of the worm. The dorsal is responsible more motor control while the laterals are for sensory. The thickest chord ventral combines the two functions.

6 Ross Digestive System Food enters and exits the worm in this order: oral cavity, pharynx, intestines, anus Roundworms have no stomach The oral cavity is coated with a tough material called cuticle

7 Ross Excretory System Longitudinal excretory ducts. The waste is simply filtered through these ducts and taken outside of the worm. In simpler species, a unicellular gland called a renette cell pumps out toxins through an excretory pore.

8 Muscle System/Locomotion
Ross Muscle System/Locomotion Underneath the epidermis lies a layer of muscle cells. These muscles are longitudinal (test question), meaning that they are unable to elongate the body and do not inch like earthworms or snakes do. Their movement is characterized by alternating contractions of the muscle, which looks like a thrashing or a wagging tail.

9 Ross Skeletal Type The cuticle is the closest thing a roundworm has to a skeleton because the cuticle is used for movement and support. There are no distinct joints.

10 Sensory structures/features
Liviu Cengher Sensory structures/features Sensory Bristles along the cuticle. (sensilla) Sensory organs at posterior, involved in reproduction. (phasmids) Two Amphids located on the head 1.1 1.2 1.5 1.3 1.4 Amphids: Specialized Sensillia that can sense better than normal ones on the cuticle 1.7 1.8 1.6 Bibliography for this slide: 11.1 Created by Livius Cesar Cengher 11.2 11.3 11.4 11.5 11.6 11.7 11.8

11 Reproduction Both sexes possess one or two tubular gonads
Liviu Cengher Reproduction 2.1 Both sexes possess one or two tubular gonads In males, the sperm are produced at the end of the gonad, and migrate along its length as they mature. In females, the ovaries each open into an oviduct and then a glandular uterus Female Rep. Organ Male Rep. Organ 2.3 2.2 Bibliography for this slide: 12.1 12.2 12.3

12 Semi Permeable Cuticle
Liviu Cengher Gas exchange 3.1 Diffusion across the cuticle. O2, CO2, ETC. 3.2 O2 CO2 Semi Permeable Cuticle Bibliography for this slide: 13.1 13.2

13 Other unique features, sketches
Liviu Cengher Other unique features, sketches 14.1 They have a tough Cuticle (a mass of cellular material and nuclei without separate membranes that coats the body) which is periodically shed. The word "nematode" comes from a Greek word Νεμα (Nema), which means "thread”. Nematodes are able to suspend their life processes completely when conditions are unfavorable, then return to life when favorable conditions return. This is called cryptobiosis. Tough! * * 14.3 * 14.2 * * * Bibliography for this slide: 14.1 14.2 * PowerPoint Clipart

14 Ross Pictures

15 Test Question 1 Food is processed in nematodes in which order?
Ross Test Question 1 Food is processed in nematodes in which order? Pharynx, stomach, intestines, anus Oral cavity, pharynx, stomach, excretory ducts Pharynx, intestines, excretory ducts Oral cavity, intestines, anus Oral cavity, pharynx, intestines, anus ANSWER: E.

16 Test Question 2 Nematodes have all of the following systems EXCEPT
Ross Test Question 2 Nematodes have all of the following systems EXCEPT Excretory Circulatory Skeletal Nervous Digestive ANSWER: B.

17 Test Questions 3 & 4 Answers: 3. C 4. A Those Things Liviu Cengher
Which of these breathe through their tough cuticle? Onychophora Arthropoda Nematoda Mollusca Which of these feel through sensillia on their tough cuticle? Brachiopoda Cnidaria Annelida Those Things 3. C 4. A (because our ppt is on nematodes obviously) Answers:

18 Bibliography Liviu Cengher
Info: Pictures: 11.1 Created by Liviu Cengher 11.2 11.3 11.4 11.5 11.6 11.7 11.8 13.1 13.2 14.1 14.2 * PowerPoint Clipart

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