Mollusks, Echinoderms, and Arthropods Biology 11

Phylum Mollusca pgs Examples: snails, clams, oysters, squid Examples: snails, clams, oysters, squid Habitat: mostly aquatic and terrestrial Habitat: mostly aquatic and terrestrial 7 classes: Gastropods, Pelecypod, Cephalopods, Polyplacophora, Scaphopod, Aplacophora, Monoplacophora 7 classes: Gastropods, Pelecypod, Cephalopods, Polyplacophora, Scaphopod, Aplacophora, Monoplacophora

Body plan Development Bilateral Symmetry Bilateral Symmetry Three germ layers Three germ layers True coelom True coelom Protosomes pg 428 Protosomes pg 428 Basic body plan includes: Basic body plan includes: Foot – for locomotion Foot – for locomotion Mantle – hanging tissue Mantle – hanging tissue Shell – internal or external, calcium carbonate Shell – internal or external, calcium carbonate Gills – respiratory structures (aquatic) Gills – respiratory structures (aquatic) Visceral mass – internal organs Visceral mass – internal organs

Mollusks Systems Sexual Reproduction – Hermaphroditic with cross fertilization, or separate sexes. Sexual Reproduction – Hermaphroditic with cross fertilization, or separate sexes. Circulatory System - Closed Circulatory System Circulatory System - Closed Circulatory System Digestion – Radula (a rough tongue) and filter feeding. A complete digestive tract. Digestion – Radula (a rough tongue) and filter feeding. A complete digestive tract. Nervous System – Primitive brain and light receptors or eyes. Nervous System – Primitive brain and light receptors or eyes. Respiration – Gills are covered by the mantle. Respiration – Gills are covered by the mantle.

Phylum Echinodermata pgs Echinos =spiny or bristly Echinos =spiny or bristly Derm= skin Derm= skin Examples: Starfish, sea urchin, sand dollar, sea cucumber Examples: Starfish, sea urchin, sand dollar, sea cucumber Habitat – aquatic actually means fresh water so they actually live in MARINE environments. Habitat – aquatic actually means fresh water so they actually live in MARINE environments.

Water Vascular system The major unifying characteristic of echinoderms is their water vascular system. The major unifying characteristic of echinoderms is their water vascular system. Locomotion and feeding are accomplished by this system, which operates much like a hydralic pump. Locomotion and feeding are accomplished by this system, which operates much like a hydralic pump.

Echinoderm Echinoderms are the closest relatives to Chordates. It may not seem so at first, but looking closely at embryological evidence, it is believed that chordates and echinoderms shared a common relative. This relative is believed to have been something along the lines of sea urchin - an orgasnism a bit larger than a golf ball with spines extending radially. Interesting little creatures, they aren't especially intelligent. In fact, they don't do much of anything. Echinoderms are the closest relatives to Chordates. It may not seem so at first, but looking closely at embryological evidence, it is believed that chordates and echinoderms shared a common relative. This relative is believed to have been something along the lines of sea urchin - an orgasnism a bit larger than a golf ball with spines extending radially. Interesting little creatures, they aren't especially intelligent. In fact, they don't do much of anything.

Keep in mind that "close" is a relative term. New York and Sydney are close compared to the distance between the earth and Jupiter. It is all a matter of context. In evolution, the context is a matter of many millions of years. Keep in mind that "close" is a relative term. New York and Sydney are close compared to the distance between the earth and Jupiter. It is all a matter of context. In evolution, the context is a matter of many millions of years.

Body plan Development Bilateral Symmetry in larvae, Bilateral Symmetry in larvae, Radial Symmetry in adults (Secondarily derived pentaradial symmetry. What does that mean? It means that echinoderms tend to be pentaradially symmetric. The secondarily derived portion of that means that they switch from being bilaterally symmetric to radially symmetric as they mature. This is of no consequence to taxonomists, they use the symmetry at the larval stage. Radial Symmetry in adults (Secondarily derived pentaradial symmetry. What does that mean? It means that echinoderms tend to be pentaradially symmetric. The secondarily derived portion of that means that they switch from being bilaterally symmetric to radially symmetric as they mature. This is of no consequence to taxonomists, they use the symmetry at the larval stage. Three germ layers Three germ layers True coelom True coelom Deuterosomes pg. 432 Deuterosomes pg. 432

Echinoderm Systems Water vascular system – unifying systems between all echinoderms. Allows for some locomotion. Water vascular system – unifying systems between all echinoderms. Allows for some locomotion. Circulatory System – open circulatory system Circulatory System – open circulatory system Digestion – one way digestive tube. Filter feeding and ingestion through the mouth. Digestion – one way digestive tube. Filter feeding and ingestion through the mouth. Nervous System – oral and radial nerve cords but NO Brain. Nervous System – oral and radial nerve cords but NO Brain. Respiration – diffusion Respiration – diffusion Reproduction- Echinoderms are monoecious, that means that the sexes are separate. Males are males, females are females. There is no ambiguity. However, with echinoderms, the sexes are not readily apparent using the unaided eye. Reproduction- Echinoderms are monoecious, that means that the sexes are separate. Males are males, females are females. There is no ambiguity. However, with echinoderms, the sexes are not readily apparent using the unaided eye.

Phylum Arthropoda Pgs Arthropoda = jointed appendages Arthropoda = jointed appendages Examples: insects, crayfish, spiders Examples: insects, crayfish, spiders Habitat: ubiquitous (almost everywhere!) Habitat: ubiquitous (almost everywhere!) Largest animal phyla Largest animal phyla 4 subphyla: 4 subphyla: Trilobitomorpha, Chelicerata, Uniramia, Crustacea, Trilobitomorpha, Chelicerata, Uniramia, Crustacea,

Body Plan development Bilateral Symmetry Bilateral Symmetry Three germ layers Three germ layers True coelom True coelom Various stages of metamorphosis Various stages of metamorphosis Segemented bodies, all include a head, thorax, abdomen and a chitin exoskeleton. Segemented bodies, all include a head, thorax, abdomen and a chitin exoskeleton. Developed nervous systems, compound eyes or photoreceptors etc. Developed nervous systems, compound eyes or photoreceptors etc.

Arthropod Systems Sexual reproduction – separate sexes Sexual reproduction – separate sexes Circulatory System – Open circulatory system Circulatory System – Open circulatory system Digestion – one way digestive tube, consisting or a foregut, midgut and hind gut. Pg 438 Digestion – one way digestive tube, consisting or a foregut, midgut and hind gut. Pg 438 Nervous System – true brain with two ventral cords Nervous System – true brain with two ventral cords Respiration – tracheal system and gills Respiration – tracheal system and gills

Application Questions (to be completed for homework) Read Pgs and do practice questions on Pg 434, Questions #2, 3, 4, 7, 8 Read Pgs and do practice questions on Pg 434, Questions #2, 3, 4, 7, 8 Read Pgs and do practice questions on Pg 440, Questions #1, 2, 3, 4 and Pg 442 Question #5 Read Pgs and do practice questions on Pg 440, Questions #1, 2, 3, 4 and Pg 442 Question #5