Lab 17- The Deuterostomes: Phyla Echinodermata and Chordata

1.)Understanding early embryological development in Echinodermata 2.) Recognize the morphological features that distinguish the 5 classes of Echinodermata. 3.) examine the morphology of Asterias (a sea star) and understand how this organism moves. 4.) know the characteristics of phylum Chordata 5.) Know the classification of chordates by subphylum. 6.) Examine the morphology of Perca (yellow perch) a typical bony fish.

What does it mean for an organism to be a deuterostome?

They develop their anus first and then their mouth! They have a well developed endoskeleton.

What are the two phylum we look at that are endoderms?

chordata and echinodermata

Echinodermata are intervertebrate. What does this mean?

This means that they do not have a vertebrae (spine).

What type of symmetry do echinodermata have?

bilateral

What is their dermal skeleton called?

ossicles

What type of vascular system do echinodermata have?

a water vascular system!

What do they do with tube feet?

They use it for locomotion, respiration, and food acquisition.

Deuterostome Development

(broken down into 3 parts) What are the 3 parts?

1.) Mitosis

2.) Morphogenesis

3.) Differentiation

What are the characteristics of Echinodermata?

They are sea urchins, sea stars, sea cucumbers, sand dollars, and sea lilies.

They have ossicles (bony plates under the skin).

They have a dermal skeleton.

They have tube feet.

They have radial symmetry.

They have true coeloms and a water vascular system.

Asteroidea (sea stars)

General info

• range of 5-25 arms usually spiky

• found along Atlantic Coast of North America

• crawl on the shallow bottom or in tide pools among rocks

• Prey on Oysters!

• REGENERATE

Aboral Surface- faces up

• side without the mouth

Oral surface- faces the ground

• tentacles extend out from the mouth

**Spines are extensions of small calcareous plates (OSSICLES) that lie buried beneath the surface- form the DERMAL SKELETON

Class Crinoidea (feathers and sea lilies)

-flower-like bodies with branched arms

• OLDEST

• attack to sea floor on stems (pointing their oral surfaces up)

• filter feeders!!! use their many arms to trap food particles

Ophiuroidea (Brittle Stars)

• body with central discs

• 5 distinct, slender, flexible, jointed arms- allows arm to move freely- enabling them to crawl rapidly or swim

• ARMS REGENERTED

Echinoidea (sea urchins and sand dollars)

Aboral and Oral side

cylindrical or disc-shaped body in a shell of fused plates

-bear movable spines

-grazers, scrape algae from surfaces

PURPOSE OF SMALL HOLES:

• they have millions of tube feet that are used for movement, gripping, waste extraction and respiration

Aboral (top side)

Oral (bottom side)

5 Petalloids (ambulance)- (the rings!)

• they have 2 rows or respiratory podia (feet)

Lunules- holes that go through each side

5 branching food grooves with tube feet- push food to the mouth & move the sand dollar

Holothuroidea (sea cucumbers)

wormlike body with NO Arms or Spine

-mouth is at center with tentacles surrounding it that are modified tube feet

-eat plankton or dead organic matter.

Water Vascular system of Asteroidea

Tube foot

• made up of the Ampulla and Podium

• Ampulla- squeezes water is forced into the podium which thens expands and contacts the substrate

• to contract- the muscles shorten the podium

Asteroidea Nervous System

• radial nerve

• nerve ring

• ganglion

• tube feet

2 Part Stomach

Pyloric Stomach - stomach on the inside that digests and breaks down nutrients

Pyloric Cacea- long tube-like structures used for digestion

Cardiac stomach- spits out to consume and digest prey.

Starfish Gas Exchange

Sea Star Wasting Syndrome

bacteria is sucking up the sea stars oxygen causing tissue decay and death

Chordata Characteristics (4 Major Characteristics)

1.)Notochord

• long flexible rod of mesoderm

• replaced by a vertebrae made of backbone

2.)Dorsal, Hollow Nerve Cord

• Ectodermal tissue that forms a spinal cord

3.)Postanall tail

• Muscle and Skeletal elements provide proposal forces

4.) Pharyngeal Slits

• feeding devices in invertebrates and gas exchange in aquatic vertebrates & jaws + hearing in vertebrates

Cephlacordata- Amphibious (Sea lancelet)

• shows all 4 chordate characteristics

• burrow in and filter feeder

• gas exchange takes place across the gills and skin

• open circulatory system but no heart

• well developed coelom

• muscle segments called myotomes!

Amphibious (sea lancelet)

Urochordata (Tunicates)

All 4 characteristics of Chordata!

• Attached to rocks or free floating

• Filter feeders!

  • gills catch food in cilia and pass it to the stomachs!

• neural tube and notochord are lost in the sedentary adult but it possess a primitive circulatory system

• 1.)Water enters through inccurent canal in the pharynx!

• 2.) food goes to digestive system!

• 3.)Water exists through excurrent canal!

Larval stage of Urochordata

Larval Stage of Tunicates

Vertebrata (bony fish- perch fish included!)

vertebrate colum(aka backbone)!

• have jaws

• have lungs

• stronger legs

• eggs with membranes

Yellow Perch

• bony exoskeleton with a hard matrix of calcium phosphate

• it is able to float because its bladder helps it maintain equilibrium

Different Fin Locations

More Fin Locations

Circulatory System

Label the Image!!!

Label the Image!!

Label the Image!!

External Perch Fish Anatomy

• External nares (nostrils)

• internal ears

  • located near the brain

  • have semicircular canals for balancing organs

• operculum

  • posterior to each eye and acts as a protective covering for the respiratory gills

• lateral line

  • extends along each side of the perch

  • detects vibratory currents

Fins- used in swimming, equilibrium, and steering

• Dorsal

• Caudal

• Anal

• Pectoral Fins