Chapter 28: Arthopods & Echnioderms Ridgewood High School

Arthopod Characteristics  Segmented body  Tough exoskeleton  Jointed appendages Examples:  Insects  Crabs  Centipedes  spiders

Arthropods  Exoskeleton: tough external covering made up of chitin (proteins and carbohydrates) Land-dwelling have waxy covering  Appendages: structures such as legs and antennae that extend from the body.

Arthropod Evolution  First Arthropod appeared more than 600 million years ago.  Today: Fewer body segments Highly specialized appendages for feeding and movement Trilobite

Arthropod: Feeding  Herbivores, carnivores and omnivores  Bloodsuckers, filter feeders, detritivores and parasites  Mouth Parts Pincers Fangs Sickle shaped jaws

Arthropod: Respiration  Terrestrial Arthropods Breath through branching tracheal tubes that extend throughout the body. Air enters and leaves the tracheal tubes through spiracles.  Spiracles: small openings located along the side of the body. Spiders: respire using book lungs  Book Lungs: are organs that have layers of respiratory tissue stacked like pages of a book

Arthropod: Circulation & Excretion  Open-Circulatory System Well developed heart pumps blood through arteries that branch and enter the tissues. Blood leaves the vessels and moves through sinuses.  Terrestrial Excretion- Malpighian Tubules Saclike organs that extract waste form the blood and then add them to feces or digestive wastes in gut.  Aquatic Excretion- Diffusion

Arthropods: Response  Nervous system- well developed Brain Ventral nerve cord with several ganglia (groups of nerve cells)  Ganglia coordinate the movements of individual legs and wings Sense organs  Eyes  Taste receptors (gather information from environment)

Arthropods: Movement  Well developed muscles Coordinated and controlled by the nervous system Generate force by contracting and then pulling on the exoskeleton Joints: muscles flex (bend) or extend (straighten)  Terrestrial Reproduction: internal fertilization Males either insert the sperm in female or leave it in a sac in which the female picks it up.  Aquatic Reproduction: internal /external fertilization External fertilization: eggs are released in the water and then the male sheds their sperm over the eggs.

Arthropods: Growth and Development  Exoskeleton does not grow with the animal  When they outgrow their exoskeletons, arthropods undergo periods of molting Molting: arthropods sheds its entire exoskeleton and manufactures a larger one to take its place.

Arthropods: Classification  Classified based on the number and structure of their body segments and appendages- particularly their mouthparts. Crustaceans Spiders and their relatives Insects and their relatives

Crustaceans  Primarily aquatic Crabs, shrimps, lobsters, crayfish, barnacles  Have two pairs of branched antennae  Two or three body sections  Chewing mouthparts called mandibles.

Crustaceans: Body Plan  Two body sections Cephalothorax: formed from the fusion of the head with the thorax Thorax: lies behind the head which housed most of the internal organs Abdomen: posterior part of the body Carapace: the part of the exoskeleton that covers the cephalothorax

Crustaceans  Antennae: sense organs (2 pairs) Some use it for swimming or filter feeding  Mandible: mouthpart adapted for biting and grinding food.  Gills: attached to the cephalothorax  Chelipeds: one pair of large claws that are modified to catch, pick up, crush, & cut food.  Swimmerets: flipperlike appendages used for swimming

Crustaceans: Barnacles  Sessil  No abdominal segments  No longer use mandibles  Attach themselves to rocks on the shore and in tide pools or on whales

Chelicerates: Spiders & Relatives  Horseshoe crabs, spiders, ticks, scorpions  Identified by: chelicerae (mouthparts)  Chelicerae: mouth appendage; contain fangs and are used to stab and paralyze prey.  Pedipalps: 2 nd mouth appendage; longer then chelicerae and are modified to grab prey two body sections  cephalothorax, abdomen 4 pairs of walking legs Book lungs/gills

Chelicerate: Horseshoe Crabs  Oldest living arthropods They have a heavy armored plate like crabs Anatomy similar to spiders  Body plan Chelicerae 5 pairs of walking legs Long spike like tail used for movement Size: large frying pan

Chelierate: Spiders  Feed: small arthropods to birds  Spiders: spin webs and capture flying prey  Tarantula: stalk and pounce on prey  Spiders: No jaws for chewing Uses fanglike chelierae to inject paralyzing venom in prey…liquefies the prey and ingests it into specialized pumping stomach. Spinnerets: organs that contain silk glands  All spiders produce silk (stronger then steel)

Chelicerate: Mites, Ticks, Scorpions  Mites and Ticks Small arachnids Parasitic Chelicerae are used for digging in the host and pierce into the skin  Scorpion Live in warm areas Pedipalps  enlarged into claws  Carry venomous stinger that can kill or paralyze prey Chew their food, unlike spiders

Chelicerate: Insects & Relatives  Centipedes, millipedes, insects The largest animal group with the most species alive today  Body plan Jaws One pair of antennae Unbranched appendages  Centipedes and millipedes: long, wormlike bodies composed of many leg-barring segments  Insects: compact, 3-part bodies, most adaptive for flight.

Chelicerate: Insects  Body Plan: 3- Parts Head, thorax, abdomen Three pairs of legs attached to thorax Pair of antennae and compound eyes

Echinoderms  Spiny skin  Endoskeleton (internal skeleton)  Water vascular system  Tube feet: suction cuplike structures  5-part radial symmetry (adult)  Deuterstomes (blastopore develops into anus first  Bilaterally symmetrical larvae (similar to verts)

Echinoderm: Form & Function  Water vascular system: System of internal tubes Tubes are filled with fluid, carries out many essential functions;  Repiration  Circulation  Movement Madreporite: sieve-like structure in which it opens to the outside environment (part of the water vascular system)  Connects to a ring canal that forms a circle around the animals mouth (sea stars) Tube Feet: located on the radial canal and operates like a suction cup

Echinoderms: Feeding  Five part jaw-like structures  sea urchins Scrapping algae  Tube-feet capturing  sea lilies Floating plankton  Scrap the bottom of ocean  sea cucumbers Scrap the bottom of ocean for sand and detritus  Tube-feet and muscles  sea stars Mollusks…bivalves

Echinoderms: Respiration & Circulation  Respiration: thin walls of tube feet provides surface for breathing Some use skin gills  Circulation: done through water vascular system Oxygen, food, and wastes

Echinoderms: Excretion & Response  Anus: solid wastes removed through tiny hole near mouth  Urea and ammonia removed through tube-feet thin cell walls into surrounding water.  Response: Nerve ring surrounding mouth and no head Radial nerves that connect the ring with body sections. Sensory cells: (scattered) that detect light, gravity, & chemicals released by potential prey

Echinoderms: Movement & Reproduction  Move using tube-feet and thin layers of muscle fibers Varies between groups  Reproduction: external fertilization Most species sexes are separate organisms Sperm produced by testes; egg produced by ovaries Shed into open water, Bilateral larvae swim to bottom of ocean and develop into radial symmetrical adults

Echinoderms: Groups  Sea Urchins and Sand Dollars  Brittle Stars  Sea Cucumbers  Sea Stars