An Introduction to the Phylum Cnidaria & Nematoda Invertebrates

Stages of a Cnidarian 1- Polyp 2- Medusa IMAGE LOCATION: Anatomy

Characteristics of Cnidarians -Nematocysts- small organelles used to capture prey and ward off predators, located on the tentacles -Radially symmetrical -Sexual Production in Medusae, Asexual Budding in Polyps

CNIDARIANS Anthoz oa Hydroz oa Scypho zoa Three Major Types

#1- Anthozoa Include the corals that build great reefs in tropical waters, as well as sea anemones, sea fans, and sea pens. IMAGE LOCATION: The oldest anthozoans are probably the polyp-like and sea pen- like fossils from the Vendian (late Precambrian) period.

Most hydrozoans switch between a polyp and a medusa stage, but they spend part of their lives as "jellyfish,” and they are predatory Dioecious and colonial #2-Hydrozoa IMAGE LOCATION:

#3- Scyphozoa Despite their large size, jellyfish have no head, no skeleton, and no special organs for respiration or excretion. Their life cycle involves an alternation between polyp phase and a medusa stage, though the medusa stage usually predominates. IMAGES LOCATION:

Cubozoa They appear cubic from above, and have four evenly spaced out tentacles or bunches of tentacles and well- developed eyes. IMAGE LOCATION: Arguably, Cubozoans are a 4th group

Additional Facts On Cnidarians Cnidarians have a single orifice and body cavity used for digestion and respiration. Most cnidarians prey on organisms from plankton to animals larger than themselves, however most obtain much of their nutrition from endosymbiotic algae, and some are parasitic. Cnidarians make up corals - found in warm, shallow marine waters - other cnidarians live in the depths, in polar seas and in freshwater.

Nematoda Roundworms -HABITAT -BODY STRUCTURE -SYSTEMS AND REPRODUCTION IMAGE LOCATIONS:

Habitat Nematodes inhabit nearly every geographic location on Earth Can live in extreme habitats Can be parasitic Found in soil and sediments Some can parasitize humans And Interaction With Humans

Body Structure Pseudocoelemates Tough, Covered with transparent cuticle, cylindrical, unsegmented body, pointy posterior, blunt anterior end, bilaterally symmetrical

Systems and Reproduc tion Complete digestive system No circulatory system Sexual Reproduction Has a nervous system

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