Chapter 26 Sponges and Cnidarians What is an

Chapter 26 Sponges and Cnidarians

What is an Animal? The animal kingdom is the most diverse of all the kingdoms In the animal kingdom, each major group, or phylum, has its own typical body plan Animals all share certain characteristics: They are all heterotrophs They are all multicellular Their cells are eukaryotic

What is an Animal? Animals, members of the kingdom Animalia, are multicellular, eukaryotic heterotrophs whose cells lack cell walls Over 95% of all animal species are grouped in an informal category known as invertebrates Have no backbone(vertebral column) Range in size from microscopic to many meters long Are very diverse

What is an Animal? The other 5% are considered vertebrates Have a backbone (vertebral column) Include fishes, amphibians, reptiles, birds, and mammals

What is an Animal?

How do Animals Survive Animals carry out the following essentials functions: Feeding, Respiration, Circulation, Excretion, Response, Movement, Reproduction

How do Animals Survive Feeding Herbivores- feed on plants Carnivores- feed on other animals Filter feeders -aquatic animals that strain the tiny floating plants and animals from the water around them Detritivores- feed on decaying pieces of plant and animal material called detritus Parasites- a symbiont that lives in or on another organism feeding on it causing it harm

How do Animals Survive Respiration Take in oxygen and give off carbon dioxide Some animals use diffusion to accomplish respiration Others have evolved a more complex use of specialized tissues and organs

How do Animals Survive Circulation Some small animals use diffusion as a means of oxygen, waste products, and nutrient transport Larger animals have a circulatory system to move materials around the body

How do Animals Survive Excretion Primary waste product is ammonia A build up of ammonia and other waste products would be fatal Most animals have an excretory system that either eliminates ammonia quickly or converts it to a less toxic substance that is eventually removed from the body Systems vary from a group of a cells that pump out water to complex organs such as the kidney

How do Animals Survive Response Respond to events in their environment using nerve cells Some cells respond to stimuli (receptors) while other s process information Nerve cell arrangement varies dramatically from phylum to phylum

How do Animals Survive Movement Some animals live their entire adult life in one spot Most are motile All have muscles or muscle – like tissues that contract and generate force when stimulated This enables motile animals to be able to move around In sedentary animals, it help in feeding and pumping of water and fluids

How do Animals Survive Reproduction Some animals reproduce sexually Creates and maintains genetic diversity in populations Improves a species ability to evolve when the environment changes Some animals reproduce asexually Mostly invertebrates Produces offspring that are genetically identical to the parent Allows animals to increase their numbers rapidly

What Animals Do to Survive

Trends in Animal Evolution Complex animals tend to have high levels of cell specialization and internal body organization, bilateral body symmetry, a front end or head with sense organs, and a body cavity

Cells specialization and internal body organization Specialized cells…tissues…organ systems…. organism Each cell type has a specific structure and chemical composition that enables it to carry out a specific function Read page 661 “Early Development” … know terms, zygote, blastula, protostome, deuterostome, anus, ectoderm, mesoderm, and endoderm

Development after Fertilization ●A cells divide to produce a hollow ball of cells called a Blastula. ●A tube called a Blastopore forms in the center of this ball. ●In Protostomes, the Blastopore develops into the mouth. ●In Deuterostomes, the blastopore forms an anus, and the mouth forms later.

Body Symmetry Sponges are the only animals that do not exhibit any body symmetry

Radial Symmetry Have body parts that repeat around the center of the body Any number of imaginary planes can be drawn through the center of the body dividing the body in equal halves Planes of Symmetry

Bilateral Symmetry Imaginary plane divides the body into 2 equal halves (right and left sides) Usually have a anterior, posterior, dorsal and ventral sides Allows for segmentation Most have external body parts that repeat on both sides The combination of bilateral symmetry and segmentation is found in 2 of the most successful animal groups …. arthropods and vertebrates Dorsal Posterior Anterior Ventral

Cephalization The concentration of nerve cells and sense organs at the anterior end of an organism Mostly found in animals with bilateral symmetry Anterior end usually called the head ●Dragonflies have their brains and other sense organs toward the front of the body. ●The end of the body comes into contact with the environment first Allowing animals to respond effectively to stimuli.

Body cavity formation A fluid filled space that lies between the digestive tract and the body wall Provides a cavity for the internal organs to be protected, grow, and expand Contain fluids involved in circulation, feeding and excretion

Sponges Best known for their dried form – natural sponges used for bathing The simplest, and most ancient animals living on earth (540 million years) Members of the phylum porifera (“pore bearers”) They have pores all over their bodies Are sensitive live in same spot their entire adult life Sponges are classified as animals because they are multicellular, heterotrophic, have no cell walls and contain a few specialized cells

Form and Function Body Plan Asymmetrical …. No front, back, left, right A large cylindrical water pump Body forms a wall around central cavity where water is continually circulated Choanocytes move water through the cavity with flagella The movement of water through the central cavity provides a simple mechanism for feeding, respiration, circulation, and excretion

Form and Function They have a simple skeleton made of tiny spicules (hard sponges) Spike shaped structure made of chalk-like calcium carbonate or glass like silica Made by archaeocytes- specialized cells in the sponge wall Softer sponges have a skeleton made of spongin A network of flexible protein fibers

The Anatomy of a Sponge http: //www. phschool. com/atschool/phsciexp/active_art/structure_of_a_s ponge/index. html

Feeding Filter feeders – shift microscopic particles from the water Digestion is intracellular Food particles engulfed by choanocytes, digested and passed on to the archaeocytes Archaeocytes transport the digested food throughout the sponge

Circulation, Respiration, & Excretion Rely on movement of water through the body cavity Dissolved oxygen diffuses into the cells from the water CO 2 and other nitrogenous waste diffuse into the water and are carried away

Response No nervous system to respond to environment Many sponges produce toxin that helps protect them from predation

Reproduction Can reproduce either sexually or asexually Sexual Reproduction Produces both egg and sperm Fertilized inside the body – internal fertilization Sperm carried o water currents to another sponge Archaeocytes carry sperm to egg in wall of sponge

Reproduction Zygote develops into a larva Immature stage of organism Motile Carried on water currents to settle on sea floor

Asexual Reproduction Reproduce by budding or producing gemmules Budding a piece breaks off, settles on sea floor, and grows into a new sponge Gemmules groups of archaeocytes surrounded by a tough layer of spicules Can survive harsh conditions When conditions are favorable, they grow into a new sponge

Steps in Sexual Reproduction

Ecology Have an irregular shape Many are large Ideal marine habitats for marine animals such as sea snails, shrimp, etc. Mutualistic relationships with bacteria, algae, and plant-like protest Live attached to the sea floor Photosynthetic organism have a Mutualistic relationship with sponges to help provide some of its energy requirements Sponge helps to amplify light for photosynthetic organism

Cnidarians A group that includes hydras, jellyfishes, sea anemones, and corals Found in oceans all over the world Some live as individuals while others live in colonies Are soft-bodied, carnivorous animals that have stinging tentacles arranged in circles around their mouths Are the simplest animals to have body symmetry and specialized tissues Get their name from cnidocytes Stinging cells located in their tentacles Used for defense and to capture prey Contain nematocyst A poison filled stinging structure that contains a tightly coiled dart thousands of nematocyst in the tentacles paralyze or kill prey

Cnidarians

Form and Function Body Plan Cnidarians are radially symmetrical Have a central mouth surrounded by tentacles Has a life cycle that has 2 stages: polyp and medusa

Polyp and Medusa Polyp Cylindrical body Mouth and tentacles pointed upward Sessile Like a Hydra Medusa Bell shaped body Mouth and tentacles pointed down Motile Like a Jellyfish

Polyp and Medusa Both polyps and medusas have a body wall that surrounds the gastrovascular cavity Internal cavity Has only one opening…. the mouth Digestion begins here The inner lining is called the gastroderm Where digestion takes place Epidermis –the outer layer of cells Mesoglea-layer between the gastroderm and the epidermis

Polyp and Medusa

Feeding Pulls prey into mouth and gastrovascular cavity Food enters and leaves through the mouth Digestion is extracellular Partially digested food is absorbed by the gastroderm…this is where digestion is completed Undigested materials are passed out through the mouth

Respiration, Circulation, & Excretion Nutrients are transported by diffusion Respiration and waste removal are also accomplished by diffusion

Response Both polyps and medusas gather information using a nerve net A loosely organized network of nerve cells that allow cnidarians to detect stimuli…. touch, etc. Distributed uniformly throughout the body Has statocyst Sensory cells that help determine the direction of gravity Has ocelli Eyespots made of cells that detect light

Nerve Net

Movement Different cnidarians move in different ways…water current, hydrostatic skeleton A layer of circular muscles and a layer of longitudinal muscles Pushes water out of the gastrovascular cavity to propel the organism Jellyfish move by means of jet propulsion

Reproduction Most cnidarians can reproduce both sexually and asexually Asexually Polyps reproduce by budding One type is when the bud breaks off and falls to the sea floor and grows into a new polyp Another type is when the polyp produces many new medusas that separate and become new individuals Sexually Takes place with external fertilization Outside the females body Each individual is either male or female Females release the eggs into the water … the male releases the sperm into the water…zygote grows into a free swimming larva attaches to a hard surface and grows into a polyp Next the polyp buds and releases a medusa that begins the cycle again

Life Cycle of Aurelia

Groups of Cnidarians include jellyfishes, hydras and their relatives, sea anemones, and corals Jellyfishes Class Scyphozoan Means “cup animal” Live primarily as medusas Can be very large Reproduce sexually

Jellyfish using Bioluminescence

Hydras and their Relatives Class hydrozoa Polyps grow colonies that expand more than a meter Within a colony, polyps are specialized to perform specific functions Portuguese man-of-war is example of colony with specialized polyps Most common freshwater hydrozoans Differ from other hydrozoans because the lack a medusa stage Can reproduce asexually or sexually Get nutrition by either prey or symbiotic photosynthetic protist that live in their tissues

Sea Anemones and Coral Class entozoan-”flower animal” Has only the poly stage All have a central body surrounded by tentacles Species are colonial Sea anemones Solitary polyps Use nematocyst to catch prey

Coral Polyps Look like anemones but are colonial Hard corals are formed by the colonies secrete calcium carbonate as an underlying skeleton (limestone) Colonies grow slowly and may live for thousands of years Many colonies growing together may produce coral reefs Can reproduce both asexually and sexually

Ecology of Corals Distribution of corals is determined by water temperature, water depth, and light intensity The stony or hard corals are formed in high levels of light Corals depend on a symbiotic relationship with photosynthetic algae Symbiont provide as much as 60% of energy the corals need to survive

Ecology of Corals Things that adversely affect coral reefs: Recreational divers Silt and sediments from farming construction, etc. Chemical pollutants Overfishing Coral Bleaching High temps kill the algae on the corals leaving behind transparent cells atop white skeletons

Chapter 26 Questions 1. What is the difference between a protostome and a deuterostome? 2. What are 3 germ layer of animal embryo's and what do they develop into? 3. What is the difference between radical symmetry and bilateral symmetry? 4. What are choanocytes? 5. What are archaeocytes and what do they make?

Chapter 26 Questions 6. What are Cnidarians? 7. What are cnidocytes and nematocyst and what are their relationship? 8. What are the 2 life cycles of cnidarians and describe each? 9. What is a nerve net? 10. What is a hydrostatic skeleton and how does it help cnidarians move?

Chapter 26 Questions 11. What is external fertilization? 12. What are 4 groups of animals included in the phylum cnidaria? 13. Describe Jellyfishes 14. Describe Hydra 15. Describe sea anemones and corals 16. N. ame 4 things humans do to damage coral reefs