DIVERSITY OF ANIMALS INVERTEBRATES Flashcards

Question

provide examples of cnidarians

Answer 1

- have specialized stinging cells located around the mouth and tentacles which can immobilize prey with toxin - have hairlike projection that are sensitive to touch, when touched, the cells fire the toxin- containing coiled threads that can stun the predator or prey

Answer 2

Medusae are motile with the mouth and tentacles hanging from the bell-shaped body

Answer 3

- two tissue layers include outer layer and inner layer lining the digestive cavity - there are differentiated cell types in each tissue layer, like nerve cells, enzyme-secreting cells, and nutrient- absorbing cells - nervous system is primitive, with nerve cells scattered across the body in a network - nerve cells carry signals from sensory cells and to contractile cells - have extracellular digestion, with digestion completed by intracellular digestive processes

Answer 4

Food is taken into the gastrovascular cavity, enzymes are secreted, and the cells lining the cavity absorb the nutrients * gastrovascular cavity has only one opening that serves as both a mouth and an anus (incomplete digestive system) * Gas exchange, circulation, and excretion occur by diffusion between cells and the water

Answer 5

- are acoelomate organisms that include free -living and parasitic forms

Answer 6

bodies contain no cavities or spaces between the outer surface and the inner digestive tract

Answer 7

- have three embryonic germ layers - have an incomplete digestive system with opening for both food intake and waste output - nervous system with a pair of nerve cords running the length of the body a large concentration of nerve cells at the anterior end of the worm

Answer 8

enzymes secreted by cells lining the tract, and digested materials taken into the same cells by phagocytosis

Answer 9

- free living marine or freshwater species - species that are parasites of fish exteriors - species that are parasites in the interiors of mollusks and other groups including humans and spend part of life cycle in mollusks

Answer 10

* nematodes, or roundworms, possess a pseudocoelom and consist of both freeliving and parasitic forms * Present in all habitats and extremely common, although usually not visible * Most nematodes look like slender tubes, tapered at each end * Nematodes have a complete digestive system with a distinct mouth and anus * nematode body is encased in a cuticle, a flexible but tough exoskeleton, or external skeleton Cuticle made of chitin * exoskeleton provides protection, but also restricts growth * Exoskeleton must be continually shed and replaced as the animal increases in size excretory system is not specialized and wastes are removed by diffusion * Most nematodes have nerve cords that run along the length of the body and fuse in a ring around the head and tail * Muscles under the epidermis permit only side-to-side, wavelike undulation of the body * Nematodes have a diversity of sexual reproductive strategies depending on the species * Can be monoecious (one sex), dioecious (separate sexes), or may reproduce asexually by parthenogenesis

Answer 11

* Arthropods are one of the most successful taxonomic groups on the planet * Have a large central cavity, a hard exoskeleton and jointed appendages * hard chitin exoskeleton covering their bodies must be periodically shed and replaced for them to increase in size arthropods have a segmented body with fusion of certain sets of segments to give rise to functional segments * The open circulatory system: blood bathes the internal organs rather than circulating in vessels * has a two-chambered heart

Answer 12

Book lungs: internal stacks of alternating air pockets and tissue shaped like the pages of a book Book gills: external structures similar to book lungs with stacks of leaf-like structures that exchange gases with the surrounding water