BIOL 1002 Crousillac Spring 2014 Exam 2 Learning Objectives Chapter 23 Invertebrates Understand the key features of animals o Multi cellular o No cell wall o Obtain energy by consuming other organisms o Most produce sexually o Motile at some point in their life o Able to respond rapidly to external stimuli o Actual tissues began to appear where there weren t before and body symmetry caused them to branch off Also the appearance of tissues Be able to explain the difference between radial and bilateral symmetry o Symmetrical animals have an upper dorsal surface and a lower ventral surface o Radial symmetry can be divided into roughly equal halves by any plane that passes through the central axis however you divide it in half it would be the same o Bilateral symmetry can be divided into mirror image halves only along one plane that runs down the midline Know the major animal phyla and distinguishing characteristics of each o Animals probably originated from ancestral protists o 27 phyla of animals o Most are invertebrates lack a vertebral column o Less than 3 of all known animals are vertebrates o Phylum Porifera Sponges Immobile Reproduce asexually by budding where the adult produces miniature versions of itself that drop off and assume an independent existence Also produce sexually through fusion of sperm and eggs No true tissues and organs o Body perforated by tiny pores through which water passes and by fewer large openings through which water is expelled o As water passes through the sponge oxygen is extracted and microorganisms are filtered out and digested by individual cells Some sponges contain chemicals useful to humans such as treatment for AIDS patients and promising new cancer drugs o Phylum Cnidarian hydrozoans Well armed predators such as sea jellies anemones corals and Mostly marine and are all carnivorous predators Most lack true organs and have no brain but rather a network of nerves that controls movement and feeding behavior Have stinging cells called cnidocytes that are used to capture prey and for defense Contain a finely coiled fragment that is expelled when the trigger is touched o Some inject poison others stick it to the prey to entangle it o The venom can cause extreme pain or death in humans Box jellyfish o Phylum Ctenophora Comb jellies b c they use cilia to move Carnivorous Can release both sperm and eggs considered ASEXUAL o Phylum Plathelminthes Parasitic or free living Include flatworms Non parasitic free living flatworms inhabit aquatic and moist terrestrial habitats Can reproduce both ways but are mostly hermaphrodites Have organs but no respiratory and circulatory systems Have a distinct head with sensory organs Their nervous system consists of clusters of nerve cells called ganglia in the head forming a simple brain In the absence of a respiratory system gas exchange is accomplished by diffusion between body cells and the environment Some are harmful to humans Tapeworms o Phylum Annelida Segmented worms Produce sexually Some are hermaphroditic Some annelids reproduce asexually through fragmentation which is when the body breaks into two pieces and each of which regenerates the missing part o Phylum Mollusca Most mollusks have shells and include clams snails and cephalopods Produce sexually Some species have separate sexes and others are hermaphroditic Know the 3 classes of mollusks and be able to give examples of each o Gastropods One footed crawlers which include snails and slugs Muscular foot for locomotion They may possess a shell but not all are shelled They feed using a radula a flexible ribbon studded with spines that scrape algae from rocks or grasp larger plants or prey o Bivalves o Cephalopods Filter feeders which include scallops oysters mussels and clams Live in fresh water and marine habitats Have two shells that can be clamped shut by a strong muscle Filter feeders that use gills for both feeding and respiration Most have a muscular foot used for burrowing or for attaching to rocks Marine predators which are octopuses nautiluses cuttlefish and squids Predatory marine carnivores Large complex brains and are capable of learning Possess highly developed sensory systems and some have shell but most do not Have tentacles with chemosensory abilities and suction disks used for locomotion and to capture prey Some release ink to escape from predators Understand the key features of arthropods including what an exoskeleton is and the process of molting o Phylum Arthorpoda Most diverse and abundant group Have appendages and an exoskeleton which is composed of protein and Insects arachnids myriapods and crustaceans chitin Exoskeleton protects against predators Provides for a range of movement of the appendages Provides a watertight covering Can be shed so the animal can grow Complex sensory and nervous systems responsible for finely coordinated movement and complex behaviors Compound eyes chemical and tactile receptors 360 vision Insects are the only flying invertebrates most abundant and diverse ability to fly which allows them to escape and find lots of food Some inject paralyzing venom into prey o Phylum Nematoda Roundworms are abundant and mostly tiny Most are microscopic but some parasitic forms reach a meter in length Reproduce sexually Most are free living non parasitic and break down organic matter Some are parasitic Hookworm cause bleeding Heartworms Trichinella cause bleeding and muscle damage o Phylum Echinodermata Calcium carbonate skeleton Reproduce sexually Can regenerate lost body parts Fertilization is external Includes sand dollars sea urchins sea stars sea cucumbers and sea lilies Understand the defining characteristics of the 3 major groups of insects Divided into 3 groups Butterflies and moths o Closely tied to the evolution of flowering plants Bees ants and wasps o Stingers which inject venom into the victim of a sting o Complex social behavior Beetles o 1 3rd of all insect species o Hard protective exoskeleton structure Understand key characteristics of arachnids myriapods and crustaceans Predatory meat eaters Include spiders mites ticks and scorpions o Arachnids Have no antennae 8 walking legs Most are carnivorous o Myriapods Many legs Centipedes and millipedes Centipedes have one pair of legs per body Carnivorous Millipedes have two pairs of legs per body Feed on decaying vegetation o Crustaceans Aquatic and include crabs crayfish lobsters shrimp and barnacles Exoskeleton Walking legs Chapter 24 Vertebrates Understand
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