Deuterostomes Overview

Deuterostomes

• Echinoderms - radial symmetry in adults, calcium carbonate endoskeletons, water vascular system for movement and feeding, can regenerate body parts
• Hemichordates - worm-like, possess a proboscis, collar, and trunk, have a dorsal nerve cord and pharyngeal slits, marine filter feeders
• Chordates - possess notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, all have a head, most have a skull and vertebral column
• Xenoturbellans - lack distinct body cavities, appear more similar to flatworms

Key Terms

• Notochord - flexible rod that supports the body
• Dorsal hollow nerve cord - hollow tube that runs along the back of the body
• Pharyngeal slits - openings in the throat that are used for filter feeding or gas exchange
• Post-anal tail - a tail that extends beyond the anus
• Endoskeleton - internal skeleton

Adaptations to Habitats

• Echinoderms - calcium carbonate endoskeleton provides protection and support – allowing them to move and graze on the seafloor
  • Starfish - tube feet with suction cups to grab prey and move along surfaces
  • Sea urchins - spines for protection and for moving along rough surfaces
• Hemichordates - filter feeders with pharyngeal slits that allow them to draw water and food into their mouths
• Chordates - notochord provides structural support allowing for swimming and burrowing
  • Tunicates - sessile filter feeders with specialized siphons
  • Vertebrates - strong endoskeletons, efficient nervous systems, and diverse adaptations for movement, breathing, and feeding
• Xenoturbellans - live in marine sediments and are adapted to these environments

Cell Organization

• Cells are organized into tissues
• Tissues are organized into organs
  • Epithelial Tissue - covers body surfaces and lines cavities
    • Protective - skin, lining of the digestive tract
    • Secretory - glands that release hormones, enzymes, etc
    • Absorptive - lining of the small intestine
  • Connective Tissue - supports, binds together, and protects other tissues
    • Loose Connective Tissue - found beneath skin, around organs, and in blood
    • Dense Connective Tissue - found in tendons and ligaments
    • Specialized Connective Tissue - includes cartilage, bone, lymph, and blood
  • Muscle Tissue - allows movement
    • Skeletal Muscle - attached to bones and allows for voluntary movement
    • Smooth Muscle - found in the walls of internal organs
    • Cardiac Muscle - found in the heart
  • Nervous Tissue - receives and transmits information
    • Neurons - specialized cells that conduct electrical impulses
    • Glia - supporting cells that provide nutrition and insulation to neurons

Metabolism & Environment

• Metabolism - all of the chemical reactions that occur within an organism
• Anabolism - building up of complex molecules from simpler ones, requires energy
• Catabolism - breaking down of complex molecules into simpler ones, releases energy
• Temperature Affects Metabolism - enzymes are sensitive to temperature
  • Cold Environment - metabolic rate slows down
  • Hot Environment - metabolic rate increases
• Food Affects Metabolism - food provides the energy needed for metabolism
• Sunlight Affects Metabolism - plants use sunlight for photosynthesis, which provides energy for all other organisms

Feedback Loops

• Positive Feedback Loops - amplifies a change, tends to be less common, can lead to instability
  • Example - oxytocin release during labor
• Negative Feedback Loops - dampens a change, more common, helps maintain homeostasis
  • Example - blood glucose regulation (insulin and glucagon)

Body Size & Shape

• Surface Area to Volume ratio - smaller organisms have a higher surface area to volume ratio than larger organisms
• Heat Loss - smaller organisms lose heat more quickly than larger organisms
• Metabolic Rate - smaller organisms have a higher metabolic rate than larger organisms

Feeding Mechanisms

1. • Suspension Feeding - filter feeding, using structures like cilia or baleen
   • ex. whales, barnacles
2. • Deposit Feeding - eating sediment, extracting nutrients
   • ex. earthworms, polychaetes
3. • Herbivory - eating plants
   • ex. cattle, rabbits
4. • Carnivory - eating other animals
   • ex. lions, hawks
5. • Parasitism - living inside or on another organism and feeding off of it
   • ex. tapeworms, ticks

Form & Nutrient Gain

1. • Form affects nutrient gain
   • Mouth - adapted to type of food
   • Digestive System - length and structure depend on the type of food
   • Surface Area - increased surface area in intestines for maximal absorption
   • Specialized Organs - for digestion, storage, and elimination of waste
2. • Herbivores
   • Long digestive system to break down cellulose
   • Specialized stomachs (ruminants) or intestines for digestion of plant matter

Ventilation

1. • Inhalation - air enters lungs
   • Diaphragm - muscle contracts, pulling air into the lungs
2. • Gas Exchange - oxygen diffuses from the lungs into the blood, carbon dioxide diffuses from the blood into the lungs
   • Alveoli - tiny air sacs in the lungs where gas exchange occurs
3. • Exhalation - air leaves the lungs
   • Diaphragm - muscle relaxes, pushing air out of the lungs
4. • Circulation - blood carries oxygen to the body's cells and carbon dioxide back to the lungs
   • Heart - pumps blood throughout the body

Digestion

• Digestion - the breakdown of food into molecules that can be absorbed by the body
• Mechanical Digestion - physical breakdown of food
  • Chewing - teeth break down food
  • Churning - muscles in the stomach and intestines mix and break down food
• Chemical Digestion - chemical breakdown of food by enzymes
  • Enzymes - proteins that catalyze chemical reactions

Alimentary Canal

• Mouth - chews food
• Esophagus - transports food to the stomach
• Stomach - churns food and mixes it with gastric juices
• Small Intestine - absorbs nutrients
• Large Intestine - absorbs water and forms feces
• Rectum - stores feces
• Anus - expels feces
• Accessory Organs - pancreas, liver, gallbladder

Ruminant Digestion

• Ruminants - herbivores with four-chambered stomachs
  • Rumen - largest chamber, contains bacteria that break down cellulose
  • Reticulum - traps larger particles of food for further breakdown
  • Omasum - absorbs water and some nutrients
  • Abomasum - true stomach, secretes digestive enzymes

Gastrovascular Cavities

• Cnidarians - have a gastrovascular cavity, a single opening for both eating and excretion

• Flatworms - also have a gastrovascular cavity

• Open Circulatory Systems - blood is not always contained within blood vessels, blood flows freely through cavities and organs

  • Example - mollusks and arthropods

• Closed Circulatory Systems - blood is always contained within blood vessels, allows for efficient transport of oxygen and nutrients

  • Example - annelids, vertebrates

Arteries & Veins

1. • Arteries - carry oxygenated blood away from the heart
   • Thick walls - to withstand the pressure of blood flowing away from the heart
2. • Veins - carry deoxygenated blood back to the heart
   • Thinner walls - than arteries
3. • Capillaries - tiny blood vessels where gas exchange occurs between blood and tissues
   • One cell thick - allows for efficient diffusion
4. • Venules - small veins
   • Carry blood back to heart - collect blood from capillaries

Explore the fascinating world of deuterostomes, including echinoderms, hemichordates, chordates, and xenoturbellans. This quiz covers their unique characteristics, adaptations, and essential biological terms. Test your knowledge on their anatomy and evolutionary significance.