Phylum Echinodermata Biology 11

Definition Echino- = “spiny”; dermis = “skin” Characteristics of Echinoderms: -spiny skin, covering a hard calcium carbonate plate-like endoskeleton

Definition More characteristics of Echinoderms: -water vascular system -tube feet (suction-cup like structures) -radial symmetry -deuterostomes (blastopore develops into anus) -true coelomates

Body symmetry Echinoderms have five-part radial symmetry Their larvae, however, have bilateral symmetry (like humans)

Form and Function Echinoderms have a water vascular system, filled with fluid This system consists of canals that extend throughout the body and opens to the outside through a madreporite

Water Vascular System Madreporite connects to ring canal, which connects to radial canals Attached to the radial canal are hundred of tube feet

Feeding Use of tube feet to capture prey or plankton Can be herbivores (plankton) Can be carnivores (mussels, clams) -ex. Sea stars can pry prey’s shell open, push stomach out and pour digestive enzymes into prey, then pull stomach back in

Respiration and Circulation Thin-walled tissue of tube feet allow respiration Skin gills (in some species) Circulation provided by water vascular system (carries oxygen, food, wastes)

Excretion Solid waste through anus Metabolic waste (ammonia) through tube feet and skin gills

Response Simple nervous system with no brain Have nerve rings around mouth, and radial nerves Scattered sensory cells for light, gravity, chemicals

Movement Use tube feet and muscle fibres attached to endoskeleton Some have flexible joints or movable spines Tube feet

Reproduction External fertilization Sexes are separate Sperm and eggs released into water  fertilization  larvae  adults

Groups of Echinoderms - 1 Class Echinoidea (Sea urchins and sand dollars) -have large solid plates that form a box around their internal organs

Groups of Echinoderms - 2 Class Ophiuroidea (Brittle stars) -have slender, flexible arms that can be shed to distract predators

Groups of Echinoderms - 3 Class Holothuroidea (Sea Cucumbers) -warty, moving pickles

Groups of Echinoderms - 4 Class Asteroidea (Sea Stars – most common) -creep slowly on sea floor, carnivorous, regenerative ability

Groups of Echinoderms - 5 Class Crinoidea (Sea lilies and feather stars) -filter feeders, long feathery arms

Once upon a time there was a wise man The Starfish -Anonymous Once upon a time there was a wise man who used to go to the ocean to do his writing. He had a habit of walking on the beach before he began his work. One day he was walking along the shore. As he looked down the beach, he saw a human figure moving like a dancer. He smiled to himself to think of someone who would dance to the day. So he began to walk faster to catch up. As he got closer, he saw that it was a young man and the young man wasn’t dancing, but instead he was reaching down to the shore, picking up something and very gently throwing it into the ocean. As he got closer he called out, “Good morning! What are you doing?” The young man paused, looked up and replied, ”Throwing starfish in the ocean.” “I guess I should have asked, why are you throwing starfish in the ocean?” “The sun is up and the tide is going out. And if I don’t throw them in they’ll die.” “But, young man, don’t you realize that there are miles and miles of beach and starfish all along it. You can’t possibly make a difference!” The young man listened politely. Then bent down, picked up another starfish and threw it into the sea, past the breaking waves and said- “It made a difference for that one.”

Comparing Invertebrates Chapter 29

So many INVERTEBRATES…. how much do you remember?..... Try not to look at your notes or textbook and see how much you know!

Evolutionary Trends Specialized cells, tissues, organs little - none sponges and cnidarians simple organs flatworms mollusks and arthropods organ systems

Evolutionary Trends Body Symmetry Sponges asymmetry Cnidarians and Echinoderms radial symmetry Worms, mollusks, arthropods bilateral symmetry

Evolutionary Trends Cephalization Sponges and cnidarians none Most worms and arthropods ganglia brain Certain mollusks

Evolutionary Trends Coelom Formation Sponges and cnidarians none none Flatworms Roundworms pseudocoelom Annelids true coelom Mollusks, arthropods, echinoderms true coelom

Evolutionary Trends Early Development none Sponges and cnidarians Worms, mollusks, and arthropods protostome deuterostome Echinoderms

Feeding Both: cnidarians and flatworms Simple: Intracellular digestion sponges Complex: Extracellular digestion -incomplete  complete digestive system Annelids, arthropods, mollusks, echinoderms Both: cnidarians and flatworms

Respiration Diffusion Increase in specialized organs and surface area Gills and book gills Lungs and book lungs, tracheal tubes, spiracles

Circulation Closed circulatory system: -heartlike organ forces blood through vessels throughout body Annelids, mollusks Open circulatory system: -heart pumps blood through vessels into sinuses Mollusks, arthropods Echinoderms: water vascular system

Excretion Aquatic invertebrates – diffusion sponges, cnidarians, roundworms Terrestrial invertebrates -nephridia – annelids, mollusks -Malpighian tubules – insects, arachnids

Response Centralization -nerve nets – cnidarians Cephalization -ganglia – mollusks, arthropods Specialization -eyespots, specialized sense organs to detect light, sound, chemicals, movement, direction of gravity, etc.

Movement Hydrostatic skeleton -cnidarians, annelids Exoskeleton -arthropods Endoskeleton -echinoderms

Reproduction Asexual reproduction -fragmentation, budding, division -separate sexes, or hermaphrodites -internal fertilization or external fertilization

Very good! How did you do?  The End! Very good! How did you do? 