ECHINODERMS AND CHORDATES
OBJECTIVES
1.
2.
3.
4.
5.
Examine similarities and differences from other groups.
Define the major anatomical features of certain groups.
Observe the evolutionary advances in these groups
Understand the taxonomy of these groups and subgroups
Explore the importance of deuterostomic development.
Exercise 39
ECHINODERMS
Task 1: Examine phylum Echinodermata.
 You should be well acquainted with the differences between protostomes and
deuterostomes. Use your text to determine why this embryological event was so
crucial to the evolution of all higher life forms including humans.
1. Do proc. 39.1. Answer Questions 1 and 2. After examining the external anatomy,
remove the carapace of the sea start to examine the water vascular system as well as
other internal organs.
 We are much more related to a starfish than anything we have studies previously.
Why does this seem illogical and why does it make sense?
2. Look at representatives of the other classes. Answer Questions 3, 4 and 5.
You should be able to distinguish them as Echinoderms.
 Means of assessment: quiz, wrap-up, notebook, practicals.
THE CHORDATES
Task 2: Examine chordates.
 All chordates have three characteristics in common. What are they and what are their
functions?
1. Make observations of the subphylum Urochordata. Answer question 6.
2. Make observations of the subphylum Cephalochordates. Observe as many examples
of the mentioned classes as we have on display.
 Do these organisms look much like what you consider a chordate? Why? Why are
they considered chordates?
3. Observe the subphylum Vertebrata. What are its distinguishing characteristics. Know
the major classes of Vertebrates. Answer Questions 7 through 13.
 What is the amniotic egg? What is its relative importance in the evolution of
animals? Why?
 Means of assessment: quiz, wrap-up, notebook, practicals.
ECHINODERMATA, HEMICHORDATA, AND CHODATA
Note: This is just FYI for TAs.
I. Introduction
 Deuterostomes
 Go over in table 39-1
II. Phylum Echinodermata
 Star fish, urchins, cucumbers, and crinoids.
 Exoskeleton made of calcareous plates called ossicles.
 Pentamerous radial symmetry.
 Bilateral as juveniles
 True coeloms from mesoderm
 Much more closely related to vertebrate line than all other animal previous.
 Ceolomic canal system
 Greatly reduced circulatory system
 Coelomic fluid acts as the principal medium for the transport of food and
respiration gases.
 Water vascular system----->tube feet.
 Entirely Marine and bottom dwelling.
B. Class Asteroidea (Stelleroidea)
 Star-shaped body
 5 - 25 arms.
 Flexible, spiny skeleton
 Dissect a star fish noting the parts listed in figs. 39-2 to 39-5.
C. Class Ophiuroidea
 Central disc
 Five distinct slender, jointed arms.
 Examine brittle star.
D. Class Echinoidea
• Urchins and Sand Dollars
• Cylindrical or disc-shaped body
 Fused ossicles = test
 Bearing movable spines.
• Feeding structures = Aristotle's lantern..
• Examine dissected Aristotle's lantern.
• Examine sand dollar
III. Phylum Hemichordata
 Entirely marine
 Evolutionary link between echinoderms and chordates
 Posses both echinoderm and chordate characteristics
 Wormlike
 Bilateral symmetry
 Well-developed entercoelom
 Dorsal hollow nerve cord
• Pharyngeal gill slits.
• Examine an acorn worm noting the structures in 39-9.
IV. Phylum Chordata
 At some stage in life cycle, posses pharyngeal gill slits, dorsal hollow nerve cord and:
 Notochord = base for the juvenile skeleton and vertebral column forms AROUND it.
A. Subphylum Urochordata
• Tunicates and sea squirts.
• Larvae have chordate forms
 Primitive circulatory system
• Examine larval and adult sea squirt.
B.



•
•
Subphylum Cephalochordata
Well-developed coelom
Circulatory system without a discrete heart
Fusiform body with prominent muscle segments (myotomes).
Lancelets
Examine persevered whole mount and X-section noting the parts mentioned
on pg 412 and seen in figs. 39-11 to 39-12.
C. Vertebrata
 Next lab
ARTHOROPODA and ECINODERMATA
OBJECTIVES
1.
2.
3.
4.
Shared traits with the mollucs and annelids
Major anatomical evolutionary advances in these groups
Understand the major taxonomy of these groups and subgroups
Deuterostomes
I. Introduction
•
•
•
•
Largest phylum of animals
Success = exoskeleton = chitin
• Barrier and site of attachment for muscles
• Limits size of organisms
Segmented or fused
Molting
II. Subphylum Chericerata
• Spiders and scorpions
• Chelicerae = 1st appendages = feeding structures
• Pedipalps = 2nd = capturing prey
• Cephalothorax and abdomen
• No antennae
A. Class Merostomata
• Covered by carapace and abdominal shield
• 5 pr. of walking legs, 1st = pedipalp
• 6 th legs vestigial = chilaria
• Book gills
• Telson for balance and defense
• Examine the external anatomy.
B. Class Pycnoginida
• Sea spiders
• Prominent chilicera, proboscis, and palp.
• Examine the external anatomy.
C. Class Arachnida
• Scorpions, tics, granddaddy longlegs, spiders etc.
• Chelicerae = fangs
• Pedipalps = manipulate food and sensory
• 4 pr of walking legs
• Examine the external anatomy.
• Examine preserved and living spiders.
III. Subphylum Crustacea
 2pr antennae, 1 pr. mandibles, 2 pr. maxillae, and biramous appendages
A. Class Crustacea
• Mostly aquatic
• Compound eyes
• Carapace covered cephalothorax
• Appendages:
• 1st antennae, 2nd antennae, mandibles, maxillae, maxillipeds
• 3-9 for feeding (mandible - cheliped
• 4 pr of walking legs
•
•
•
• Swimmerets or pleopods = 1st = reproductive function
• Uropods, teslon
Analogous and homologous structures
Examine the external anatomy of crayfish.
Examine the internal anatomy of crayfish.
IV. Subphylum Uniramia
• Centipedes, millipedes, and insects.
• Uniramous appendages
A. Class Chilopoda
• One pr of walking legs/segment
• Examine preserved centipedes.
B. Class Diplopoda
• Two pr of walking legs/segment
• Examine preserved millipedes.
C. Class Insecta
• Three bold regions
• largest group of orgs. Most successful = many niches = flight
• Tracheae
• Highly modified mouth parts
• Examine grasshopper external anatomy
• Examine preserved insects and use dichotomous key.
ECHINODERMATA, HEMICHORDATA, AND CHODATA
I. Introduction
 Deuterostomes
 Go over in table 32-1
II. Phylum Echinodermata
 Star fish, urchins, cucumbers, and crinoids.
 Exoskeleton made of calcareous plates called ossicles.
 Pentamerous radial symmetry.
 Water vascular system----->tube feet.
 Entirely Marine.
B. Class Asteroidea
 Dissect a star fish noting the parts listed in figs. 32-2 to 32-5.
C. Class Ophiuroidea
• Examine brittle star.
D. Class Echinoidea
• Urchins and Sand Dollars
• Fused ossicles = test
• Feeding structures = Aristotle's lantern.
• Examine Arbacia 32-6.
• Examine dissected Aristotle's lantern.
• Examine sand dollar
III.
•
•
•
Phylum Hemichordata
Dorsal hollow nerve cord
Pharyngeal gill slits.
Examine an acorn worm noting the structures in 32-7.
IV. Phylum Chordata
• Notochord = base for the juvenile skeleton and vertebral column forms AROUND it.
A. Subphylum Urochordata
• Tunicates and sea squirts.
• Larvae have chordate forms
• Examine larval and adult sea squirt.
B. Subphylum Cephalochordata
• Lancelets
• Examine persevered whole mount and X-section noting the parts mentioned
on pg 399 and seen in figs. 32-10 to 32-11.