Comparing Invertebrates Chapter 29

29-1 Invertebrate evolution Key Vocab: Invertebrate Radial Symmetry Bilateral Symmetry Cephalization Coelom Trace fossil Deuterostome An animal that does not have a backbone, or vertebral column Bill Nye Video

Treasure troves of invertebrate fossils, dating between 575 and 543 mya have been discovered in the Ediacar Hills of Australia and in Chengliang, China Echinoderm Cnidaria or Echinoderm? Triradial?

Origin of the Invertebrates Trace fossils were discovered, dating invertebrates 570-610 million years old Trace Fossils are more common than body fossils because all living things leave traces. Trace fossils give us proof of animal life from the past. Trace fossils include things like foot prints, burrows, and fossilized feces.

The First Multicellular Animals The Ediacaran fossils include some of the earliest and most primitive animals known

Edicarian Fossils Most animals were flat, platelike Absorbed nutrients from the surrounding water Some may have been photosynthetic Were segmented and had bilateral symmetry Probably simple with little internal organization

Beginnings of Invertebrate Diversity Cambrian Period: 544 mya is marked by an abundance of different fossils By the Cambrian Period, some animals had evolved shells, skeletons, and other hard body parts—all of which are readily preserved in fossils The Burgess Shale fossils show diversity not seen previously Cambrian Explosion: the ancestors of most modern Animal phyla first appeared in the fossil record

Burgess Shale Fossils Typically had body symmetry, segmentation, some type of skeleton, a front and a back end, and appendages adapted for many functions.

Invertebrate Phylogeny

Review Which period is marked by such diversity it is referred to as an “explosion” A) Ediacaran B) Cambrian C) Cryogenian

Review Animals of the Cambrian period typicaly had all of the following except… Body symmetry Segmentation Some type of skeleton A backbone

review The Burgess shale fossils are in Texas Arizona New York Canada Footprints, burrows and fossilized feces are A) resin fossils B) psuedofossils C) trace fossils D) imprints The Burgess shale fossils are in Texas Arizona New York Canada

Evolutionary Trends Specialized cells, tissues and organs Body Symmetry Cephalization Segmentation Coelom Formation Embryological Development

Specialized Cells, Tissues, and Organs Specialized cells joined together to from tissues, organs and organ systems that work together to carry out complex function

Body Symmetry Sponges lack symmetry. All others exhibit some type Radial Symmetry; body parts extend from the center of the body Bilateral Symmetry; have mirror-image left and right sides

Cephalization The concentration of sense organs and nerve cells in the front of the body Invertebrates with cephalization can respond to the environment in more sophisticated ways than can simpler invertebrates

In most worms and arthropods, nerve cells are arranged in structures called ganglia. In more complex, nerve cells form an organ called a brain

Coelom Formation A coelom is a fluid-filled body Cavity lined with mesoderm Acoelomates do not have a coelom. Pseudocoelomates have a partial coelom. Coelomates are the most complex and have a coelom.

Review Which of the following lacks symmetry? (asymmetrical) A) a sea anemone B) a grasshopper C) a crayfish D) a sponge

review The concentration of nerve cells and sense organs in the anterior end of an organism is A) coelomization B) radial symmetry C) cephalization D) asymmetry

Segmentation Over the course of evolution, different segments have often become specialized for specific functions Same structures are repeated in each body segment Also allows a animal to increase in body size with a minimum of new genetic material

Embryological Development In most invertebrates, the zygote divides to form a blastula Protostomes: the blastopore becomes the mouth Dueterostomes: the blastopore becomes the anus

Review An acoelomate is an animal that has A body cavity lined with endoderm and ectoderm A body cavity partially lined with mesoderm A body cavity completely lined with mesoderm No body cavity between their germ layers.

Review Cephalization refers to Division of the body into upper and lower sides. Concentration of sense organs and nerve cells in the front of the body Joining together of specialized cells to form tissues Formation of a body cavity between the germ layers

Review The classification of an animal as a deuterosome or a protosome is based on Its body symmetry Whether or not it has a coelom What happens to the blastopore The number of germ layers it has

review The area marked ?????? is called the… Endoderm Coelom Protosome ??????????? The area marked ?????? is called the… Endoderm Coelom Protosome

Video Octopus Sea cucumber Sea Anenome Deadly shrimp What are Inverts?

29-2 Form and Function in Invertebrates Key Vocab Intracellular Digestion Extracellular Digestion Open Circulatory System Closed Circulatory System Hydrostatic skeleton Exoskeleton Endoskeleton External fertilization Internal fertilization

review The diversity of invertebrate phyla underwent its greatest increase Before the Cambrian period During the Cambrian period After the Cambrian period Both before and after the Cambrian period

review A body cavity that forms between the germ layers is called a(n) Coelom Blastopore Mesoderm Ectoderm

To survive, all animals perform the same essential tasks: Bill Nye To survive, all animals perform the same essential tasks: Feeding and digestion Respiration Circulation Excretion Response Movement Reproduction

Feeding and Digestion Intracellular Digestion Extracellular Digestion Before food can be used for energy, the food must be broken down, or digested Intracellular Digestion Food is digested inside cells Extracellular Digestion Food is broken down outside the cells in a digestive cavity or tract and then absorbed into the body

Patterns of Extracellular Digestion Simple animals such as cnidarians and most flatworms ingest food and expel wastes through a single opening. Food is digested in a cavity through both intracellular and extracellular means Some cells secrete enzymes and absorb digested food Other cells surround particles and digest them in vacuoles Nutrients diffuse to cells throughout the body

More complex animals digest food in a tube called a digestive tract. Have a mouth and an anus

Respiration All animals must exchange Carbon dioxide and oxygen with the environment The larger the surface area, the greater the amount of gas exchange. For diffusion to occur, the respiratory surfaces must be moist.

Aquatic Invertebrates Larger invertebrates use feathery structures called gills for respiration Small invertebrates like cnidarians and flatworms diffuse gases through their tissues

Terrestrial Invertebrates Respiratory surfaces are covered with water or mucus to minimize water loss Several types of respiratory surfaces Mantle cavity; land snails Book lungs; spiders Spiracles and trachea; insects

Circulation All cells of multicellular animals require a constant supply of oxygen and nutrients Very simple organisms: diffusion More complex have some type of pumping mechanism (heart) and vessels

Two types of Circulatory Systems Open circulatory system Blood is only partially contained within a system of blood vessels Blood fills sinuses and is in direct contact with tissues

Closed Circulatory System A heart or heartlike organ forces blood through vessels that extend throughout the body Blood can be circulated more efficiently

Review The distinguishing feature of a closed circulatory system is that Its does not include a heart Blood in contained within vessels that extend throughout the body Blood is kept at low pressure Blood is circulated with less efficiency than in an open circulatory system

review In a protosome, the blastopore becomes a(n) Mouth Anus Zygote Blastula

Excretion Multicellular animals must control the amount of water in their tissues. Must get rid of ammonia Flat worms use flame cells to get rid of excess water Terrestrial conserve water and get rid of ammonia as urea excreted in urine that was formed in nephridia Some insects and arachnids have Malpighian tubules

Sexual and Asexual Reproduction Most invertebrates reproduce sexually during at least part of their life cycle. Fusion of gametes; genetic variation Many also reproduce asexually Allows the ability to reproduce rapidly when environmental conditions are favorable

Sexual reproduction External fertilization: eggs are fertilized outside the female’s body Internal fertilization: eggs are fertilized inside the female’s body

reveiw Which structures are NOT part of an excretory system? Flame cells Spiracles Malpighian tubules nephridia

review Which statement refers to sexual reproduction? All offspring are genetically identical to the parent Offspring are produced from the fusion of male and female gametes AN organism breaks into pieces that grow into new individuals New individuals are produced from outgrowths of parent’s body wall

review During development, a zygot divides repeatedly to form a (n) Endoderm Endoskeleton Blastula Germ layer

Response Three trends in the evolution of the nervous system Centralization; nerve nets consist of individual nerve cells that form a netlike arrangement Cephalization; concentration of nerve tissue and organs in one end of the body Specialization; sense organs that detect light, sound, chemicals, movement, and even electricity to help them discover what is happening around them

Movement aNd support Muscles work with some type of skeletal system Hydrostatic skeletons: muscles surround a fluid- filled body cavity that supports the muscles.

Endoskeleton: structural support inside the body Calcified plates inside echinoderms

Exoskeletons: Hard body covering made of chitin Jointed in arthropods, shells in mollusks

review An endoskeleton is a Shell of a mollusk Fluid-filled body cavity that supports the muscles Structural support located inside the body Hard body covering made of chitin

review An example of an invertebrate with a hydrostatic skeleton is a(n) Spider Sponge Sea star earthworm