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36 Cards in this Set
- Front
- Back
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Molluscs (phylum Mollusca)
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Second most numerous group of animals.
Inhabit a variety of environments. Very diverse phylum includes chitons, limpets, slugs, snails, abalones, conchs, nudibranchs, clams, oysters, scallops, squids, and octopuses. |
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Characteristics of all mollusks:
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• Three part body plan consisting of the visceral mass, the muscular foot and the mantle.
1. The visceral mass contains the internal organs including a highly specialized digestive tract, paired kidneys, and reproductive organs 2. The mantle is the covering that lies to either side of but does not entirely enclose the visceral mass. The mantle is responsible for secreting a shell (if the organism has a shell) and/or contributes to the development of gills or lungs. 3. The foot is a muscular organ that is used for locomotion, attachment, food capture or any combination of functions. • Some species also have a radula, which is a rasping tongue-like organ that has many rows of teeth used to obtain food. • True coelom but reduced in most molluscs. • Most have an open circulatory system: hemolymph is pumped into sinus cavities collectively called hemocoel. (No capillaries). Also, Blue hemocyanin is used instead of red hemoglobin • Nervous system is several ganglia connected by nerve cords. • Cephalization varies from species to species. • Mobility is also varied from species to species |
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Class Bivalvia: The Bivalves
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• Clams, oysters, mussels, scallops and shipworms.
• Protostomes; true coelums but greatly reduced. • Have a two-part shell that is hinged and held closed large muscles at either end. • Shell protects the visceral mass • No head, no radula • Have ciliated gills • Complete digestive tract • No Cephalization (or very little Cephalization) • Clams use foot for burrowing and moving forward, scallops both burrow and swim (spurts of water) |
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Species Spotlight: Clam (Anodonta)
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Learn anatomy of the clam.
The pericardial cavity is the only remains of the coelom. Have a hatchet shaped foot for burrowing and moving forward. Evolutionary point of interest: some clams and annelids have the same type of larva, the trocophore larva which reinforces the evolutionary relationship between these two phyla. |
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Other Molluscs: Gastropods (class Gastropodia): largest class of molluscs.
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• Includes snails, slugs, nudibranchs, whelks, conchs, and limpets.
• Most are marine, but there are terrestrial snails and slugs. • Gastropod means “stomach foot” • Have an elongated, flattened foot. • Most have a one piece coiled shell with the exception of nudibranchs and slugs. • Shell protects the visceral mass • Have an anterior end with well developed Cephalization • Cerebral ganglion • Eyes on the end of stalks • Land snails are hermaphroditic but engage in sexual reproduction. Have a very interesting mating behavior (somewhat violent!). • Eggs. No larva stage. Development is direct to adult physical form |
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Other Molluscs: Cephalopods (class Cephalopodia):
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• Varied in size from very small (2cm) to quite large (20 meters).
• Cephalopod means “head foot” • Tentacles and arms used to capture prey (suckers and secretions) and for some locomotion • Rapid locomotion (such as retreat from danger) by water being squeezed out of mantle cavity through a funnel. • Have a parrot-like beak to tearing food • Very well developed eyes • Very well developed sensory system, nervous system and brain. • Very intelligent and show great learning ability (particularly octopi) |
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Annelids (Phylum Annelida)
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• Commonly referred to as segmented worms
• Vary in size from microscopic to tropical earthworms that can reach 4 m long! • Earthworms, marine worms, and leeches • Show segmentation: repetition of body parts along the length of the body. • Well developed coelom that is fluid filled and serves as a hydrostatic skeleton • The hydrostatic skeleton along with segmented coelom allows for independent movement of each body segment. • Have setae, bristles that protrude from body wall. Used to anchor worm and help it move. o Oligochaetes are annelids with only a few setae. o Polychaetes are annelids with many setae |
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Species spotlight: Earthworms* (common earthworm, Lumbricus terrestris)
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Learn the anatomy of the earthworm
• Oligochaete, that have setae that protrude in pairs directly from surface of body. • Earthworms reside in soil where there is adequate moisture to keep body wall moist for gas exchange • They are scavengers • Segmentation of body • Complete digestive tract that is very specialized • Waste eliminated out an anus • Segmented internally; visible septa occur between segments • Long ventral nerve cord from brain and lateral nerves at each segment • Excretory system with nephridia; coiled tubules in each segment. • Closed circulatory system • Oxygenated blood moves anteriorly in the dorsal blood vessel which connects to the ventral blood vessel by five pairs of muscular vessels called “hearts”. • Are Hermaphroditic: male organs are testes, seminal vesicles, and sperm ducts. • Female organs are ovaries. • Clitellum is a large smooth segment that secretes mucus and helps with attachment and sperm and egg transfer while mating. Makes a slime tube that protects eggs and sperm and forms a cocoon for newly hatched earthworms. • NO larval stage. |
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Other Annelids: Marine Polychaetes :
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• Have setae in bundles on parapodia which are paddle like appendages found on most segments.
• Parapodia used for locomotion and as respiratory organs. • Some are free swimming, but most burrow into ocean bottom or in crevices in rocks. • Examples: Clam worm, Nereis. This one is predatory. • Other examples: Christmas tree worm, tube worms and feather duster worms. |
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Other Annelids: Leeches:
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• Normally freshwater habitat
• Body is dorsoventrally flattened • No setae and each body ring has several transverse grooves • Some are free-living, most are fluid-feeders that attach to open wounds of other animals • Modifications are two suckers: oral and posterior for attachment • Keep blood flowing from hosts by means of an anti-coagulant called hirudin. • Medicinal uses in surgical procedures to maintain blood flow to healing areas. |
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Roundworms (phylum Nematoda)
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• Some are free-living in soil, water, even air. Many are microscopic. Several species are larger.
• Pseudocoelomates: body cavity but not completely lined with mesoderm which means that mesoderm occurs around the body wall but not around the gut (digestive cavity). • Internal organs including the reproductive structures are within the pseudocoelom. • Most people are familiar with the parasitic varieties. |
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. Parasitic Roundworms:
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Ascaris, Trichnosis, Filarial worms, Pinworms.
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• Ascaris
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can infect humans, cats, dogs, pigs, and a number of other vertebrate animals.
Female worms are larger than smaller male worms. Male worms have a hook like curve to their posterior end. Both genders have a characteristic whip-like movement. Eggs from female enter host body by means of uncooked veggies, dirty fingers, feces and then hatch in the intestines. Juvenilles make way to blood vessels and lymph vessels and get to heart and lungs. Larva can then make way to traecha where they are swallowed and go back to intestines where they mature and feed on intestinal contents of digested food. Symptoms of infection depend on life stage of ascaris. |
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• Trichinosis
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infects humans from undercooked pork where immature Trichnella larva are encysted in muscle of pig. Heavy infection can be painful and result in death.
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• Filarial worms
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: some cause Elephantitis. Reside in lymph system vessels and block lymph fluid. Extremeties swell to monstrous sizes.
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• Pinworms
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Most common nematode parasite in US. Females migrate to anal rgion at night from large intestine of host. There they lay eggs and infection is characterized by intense anal itching especially at night.
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Diversity of the Ecdysozoans:
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A group of protostomes that includes the roundworms and arthropods distinguished by the need for organisms to periodically shed outer covering.
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Arthropods (phylum Arthropoda):
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a very large group of protostomes. Includes many classes of organisms such as Crustaceans, Insects, Centipedes, Millipeds, and Chelicerates.
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Arthropods (phylum Arthropoda):
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General Characteristics:
o Protostomes o Coelomates o Exoskeletons primarily made of chitin, a nitrogenous polysaccharide. o Jointed appendages o Bilateral symmetry as adults o Complete digestive tract |
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Exoskeleton
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rigid but jointed and mostly made of chitin. Crustaceans have calcium carbonate in their exoskeleton. Serves as protection but must be shed periodically for organism to grow in size.
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Segmentation
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Readily apparent because each segment has a pair of jointed appendages even though some segments fused into a head, thorax and abdomen.
Jointed appendages are basically hollow tubes moved by muscles and are typically highly specialized for particular functions, such as food gathering, reproduction and locomotion. Also sensory. |
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Nervous System
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Have a brain and ventral nerve chord. Head bears sense organs including two types of eyes: simple and compound. Have a well-developed sense of smell, taste, balance and hearing. Display many complex behaviors and methods of communication.
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Variety of respiratory systems
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Marine forms use gills.
Gills: Vascularized, highly convoluted, thin-walled tissue used for gas exchange. Land organisms: some have book-lungs (Horseshoe crabs) .Some have air tubes called tracheae. |
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Gills
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Vascularized, highly convoluted, thin-walled tissue used for gas exchange.
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Metamorphosis
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Drastic change in morphology and physiology that occurs as immature stage or larva becomes an adult. The larvae of arthropods eat different food and live in different environment than the adult.
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Crustaceans (Class Crustacea (sometimes also a subphylum))
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• Hard, crusty exoskeleton that contains chitin and calcium carbonate
• Head usually bears a pair of compound eyes and five pairs of appendages (so definite cephalization!) • Head appendages: First 2 pairs called antenna and antennules. These are in front of mouth. Sensory Function Other three pairs are behind mouth. 3rd pair forms the mandibles. 4th and 5th pairs form the first and second maxillae. • Biramous appendages on thorax and abdomen are segmentally arranged: one branch is the gill branch and the other branch is the leg branch. • Majority are marine. • Decapods are most familiar (10 pairs of appendages (five on head; five on thorax/abdomen are walking legs). Crabs, lobsters, crayfish, hermit crabs, and shrimp. • Copepods and krill are small, free-swimming crustaceans that feed on algae. • Barnacles are sessile crustaceans with thick, heavy, protective shells. |
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Species spotlight: Crayfish, Cambarus. The typical crustacean.
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Learn the anatomy of Crayfish.
• Has a cephalothorax covered by a carapace • Has gills • Abdominal segments have swimmerets. • In males, claspers, the first two pairs of swimmerets are modified for help during mating. • Sexes are separate in Crayfish • No metamorphosis of larvae. • Green gland is for excretory system and is located in head. • Have a coelom but is reduced to a space mainly around the reproductive organs. • Heart that pumps hemolymph containing blue respiratory pigment hemocyanin into an open system of cavities called Hemocoel. • Open circulatory system. • Have a brain and well developed nervous system. Ventral nerve cord with periodic ganglia that give off lateral nerves. • Compound eyes on movable eyestalks. • Male sperm ducts open at base of 5th walking leg • Females have ovaries at base of 3rd walking leg • Females carry eggs on their swimmerets. |
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. Insects (Class Insecta):
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Adapted for life on land. Some have secondarily invaded water habitats.
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Unique characteristics of Insects:
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• Three part body: head, thorax and abdomen
• Head bears sensory organs and mouth parts • Segmented (all arthropods are) • Six legs (three pairs) • May have wings (one or two pairs) • Most insects undergo complete metamorphosis (example: catapillars of butterflies) • Some have highly complex social behaviors (ants, bees, wasps) |
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Species Spotlight: Grasshopper. Typical insect.
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Learn the anatomy of Grasshopper.
• Some special features include spiracles (holes that are for gas exchange) located on abdomen. • Herbivores • Wings, forewings are tough and leathery and cover hindwings when folded back along body • Along the lateral surface of each side of the abdomen, there is a tympanum for “hearing” sound waves. • Females have ovipositor on posterior end for laying eggs in soil. • Malpighian tubules in excretory system • Back legs are adapted for jumping. • Open circulatory system that consists of a slender tubular heart, a dorsal aorta and a Hemocoel that receives hemolymph. • No respiratory system other than the trachea, spiracles. • Undergo incomplete metamorphosis in which immature grasshopper called a nymph resembles the adult but is different in body proportions and must undergo several molts until adult size. |
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spiracles
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holes that are for gas exchange
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Chelicerates: Includes spiders, horseshoe crabs, and scorpions.
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Inhabit a wide range of habitats from marine (horseshoe crabs) to terrestrial forms in forests, plains, deserts etc.
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Unique Characteristics of Chelicerates:
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• Fused head and thorax (cephalothorax)
• First pair of appendages is pincerlike chelicerae used for feeding and defense. • Second pair of appendages is the pedipalps which have various functions depending on species • Some Chelicerates like mites and ticks can transmit diseases like Lymes or Rocky Mountain spotted fever. Also Typhus. |
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Deuterostomes
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Blastopore forms the anus first. Review differences between protostomes and deuterostomes.
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Echinoderms (phylum Echinodermata):
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• Primarily bottom dwelling marine animals.
• 5 point radial symmetry (pentaradial) • However, larva are free-swimming, and show bilateral symmetry • Have an endoskeleton of spiny, calcium-rich plates called ossicles • Water vascular system consisting of canals and appendages. Very unique • The water vascular system functions in many ways such as locomotion, feeding, gas exchange and sensory reception • Class Asteridea is the sea stars, Class Holothuoidea are sea cucumbers and Class Echinoidea includes the sea urchins and sand dollars. Class Ophiuroidea are the brittle stars and Class Crinoidea are the oldest group consisting of feather stars. |
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Species Spotlight: Sea Star
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• Found along rocky coasts where they feed on bivalves such as clams and oysters.
• Have projections through body wall such as 1) spines from the endoskeleton that offer protection and 2) pincerlike structures around the bases of spines and keep the surface free of small particles and 3) skin gills used for respiration. • Oral surface is bottom (where the mouth is and aboral surface is the top where the anus is and the sieve plate, the entrance to the water vascular system. • On oral surface along each arm is a canal lined with tube feet which are part of the water vascular system. • Have two stomachs: the cardiac stomach and the pyloric stomach. The cardiac stomach can be pushed out of the body and into the shell of a clam to start the digestion process. • Well developed coelom contains pair of digestive glands and gonads • Genders are separate. • Nervous system consisting of central nerve ring and radial nerves • Light sensitive eye found on each arm. • NO respiratory or excretory systems, nor do they have a circulatory system like other animals. • Fluids in the coelomic cavity and water vascular system carry out these system functions |
