Presentation on theme: "By Liviu, Ross, and Yuchen"— Presentation transcript:
1 By Liviu, Ross, and Yuchen NematodaBy Liviu, Ross, and Yuchen
2 RossOverviewNematodes 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 RossPhylum & Sample AnimalsPhylum: NematodaSample animals: Roundworms. That’s it.Metazoa: Animals with fixed body planEumatzoa: All animals but spongesBilateria: Bilaterally Symmetric
4 Body Cavity and Symmetry YuchenBody Cavity and SymmetryBody 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 YuchenCirculatory and Nervous SystemThey 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 RossDigestive SystemFood enters and exits the worm in this order: oral cavity, pharynx, intestines, anusRoundworms have no stomachThe oral cavity is coated with a tough material called cuticle
7 RossExcretory SystemLongitudinal 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 RossMuscle System/LocomotionUnderneath 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 RossSkeletal TypeThe 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 CengherSensory structures/featuresSensory Bristles along the cuticle. (sensilla)Sensory organs at posterior, involved in reproduction. (phasmids)Two Amphids located on the head184.108.40.206.31.4Amphids: Specialized Sensillia that can sense better than normal ones on the cuticle220.127.116.11Bibliography for this slide:11.1 Created by Livius Cesar Cengher11.211.311.411.511.611.711.8
11 Reproduction Both sexes possess one or two tubular gonads Liviu CengherReproduction2.1Both sexes possessone or two tubular gonadsIn males, the sperm areproduced at the end of thegonad, and migrate alongits length as they mature.In females, the ovarieseach open into an oviductand then a glandular uterusFemale Rep. OrganMale Rep. Organ2.32.2Bibliography for this slide:18.104.22.168
12 Semi Permeable Cuticle Liviu CengherGas exchange3.1Diffusion across the cuticle.O2, CO2, ETC.3.2O2CO2Semi Permeable CuticleBibliography for this slide:13.113.2
13 Other unique features, sketches Liviu CengherOther unique features, sketches14.1They have a tough Cuticle (a massof cellular material and nuclei withoutseparate 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:14.114.2* PowerPoint Clipart
15 Test Question 1 Food is processed in nematodes in which order? RossTest Question 1Food is processed in nematodes in which order?Pharynx, stomach, intestines, anusOral cavity, pharynx, stomach, excretory ductsPharynx, intestines, excretory ductsOral cavity, intestines, anusOral cavity, pharynx, intestines, anusANSWER: E.
16 Test Question 2 Nematodes have all of the following systems EXCEPT RossTest Question 2Nematodes have all of the following systems EXCEPTExcretoryCirculatorySkeletalNervousDigestiveANSWER: B.
17 Test Questions 3 & 4 Answers: 3. C 4. A Those Things Liviu Cengher Which of these breathe through their tough cuticle?OnychophoraArthropodaNematodaMolluscaWhich of these feel through sensillia on their tough cuticle?BrachiopodaCnidariaAnnelidaThoseThings3. C4. A(because our ppt is on nematodes obviously)Answers:
18 Bibliography Liviu Cengher Info:Pictures:11.1 Created by Liviu Cengher11.211.311.411.511.611.711.822.214.171.124.2* PowerPoint Clipart