BIS2C: Lecture 31: Deuterosomes I: Echinoderms & Hemichordates

1. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Lecture 31:
Deuterosomes I:
Echinoderms & Hemichordates
BIS 002C
Biodiversity & the Tree of Life
Spring 2016
Prof. Jonathan Eisen
1

2. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• SLIDES AVAILABLE AT
http://tinyurl.com/BIS2CL31
2

3. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Where we are going and where we have been…
3
•Previous lecture:
•30: Triploblasts: Protostomes:
Ecdysozoans II I
•Current Lecture:
•31: Deuterosomes I: Echinoderms &
Hemichordates
•Next Lecture:
•31: Deuterosomes II: Chordates

4. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Topics ..
4
• Deuterostome innovations and uses of
these innovations
• Major Groups of Deuterostome
• Focus on Echinoderms
• Innovations
• Symmetry
• Tube feet
• Chordate Introduction

5. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animals - AKA Metazoans
5
Metazoans

6. Clicker
What evidence supports the assertion that the common
ancestor of metazoans at least colonial, if not
multicellular?
A. Comparisons of modern metazoans
B. Comparisons of metazoans to choanoflagellates
C. Neither A nor B
D. Both A and B
!6Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

7. Clicker
What evidence supports the assertion that the common
ancestor of metazoans at least colonial, if not
multicellular?
A. Comparisons of modern metazoans
B. Comparisons of metazoans to choanoflagellates
C. Neither A nor B
D. Both A and B
!7Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

8. Clicker
What is the best evidence that sponges are the deepest
branching group within the metazoa?
A. They are the most primitive animals
B. They have cells similar to those seen in
choanoflagellates
C. All other animals are more complex
D. Sponges are not bilaterally symmetric
E. Branching patterns in molecular phylogenies
!8Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

9. Clicker
What is the best evidence that sponges are the deepest
branching group within the metazoa?
A. They are the most primitive animals
B. They have cells similar to those seen in
choanoflagellates
C. All other animals are more complex
D. Sponges are not bilaterally symmetric
E. Branching patterns in molecular phylogenies
!9Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

10. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans

11. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Common
ancestor

12. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Common
ancestor
•Colonial
•Cell adhesion
systems

13. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Common
ancestor
•Colonial
•Cell adhesion
systems

14. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Common
ancestor
•Colonial
•Cell adhesion
systems

15. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems

16. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)

17. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)

18. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Eumetazoans

19. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Eumetazoans

20. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)

21. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Diploblasts

22. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Diploblasts
Triploblasts
(Bilaterians)

23. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Simplification;
loss of nervous system
Notochord
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Diploblasts
Triploblasts
(Bilaterians)

24. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Simplification;
loss of nervous system
Notochord
Bilateral symmetry along an
anterior-posterior axis;
three embryonic cell layers
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Diploblasts
Triploblasts
(Bilaterians)

25. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Simplification;
loss of nervous system
Notochord
Bilateral symmetry along an
anterior-posterior axis;
three embryonic cell layers
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Blastopore
develops into
mouth
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Diploblasts
Triploblasts
(Bilaterians)

26. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Simplification;
loss of nervous system
Notochord
Bilateral symmetry along an
anterior-posterior axis;
three embryonic cell layers
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Exoskeleton moltingBlastopore
develops into
mouth
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Diploblasts
Triploblasts
(Bilaterians)

27. Figure 31.1 A Phylogenetic Tree of the Animals
!10Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Silicaceous
spicules
Choanocytes;
spicules
Simplification;
loss of nervous system
Notochord
Bilateral symmetry along an
anterior-posterior axis;
three embryonic cell layers
Blastopore develops
into anus
Hemichordates
DEUTEROSTOMES
(Chapter 33)
Chordates
Echinoderms
Radial
symmetry
Placozoans
Cnidarians
Arrow worms
Lophotrochozoans
Calcareous sponges
Demosponges
Glass sponges
Ecdysozoans
PROTOSTOMES
(Chapter 32)
Exoskeleton moltingBlastopore
develops into
mouth
Centopheres
Sponges
(Chapter 33)
Diploblastic
animals
(Chapter 31)
Bilaterains
(triploblastic)
Eumetazoans
Unique cell
junctions;
collagen and
proteoglycans
in extracellular
matrix
Two embryonic
cell layers; nervous system
Multicellularity,
Blastula
Common
ancestor
•Colonial
•Cell adhesion
systems
Monoblasts
(Sponges)
Diploblasts
Triploblasts
(Bilaterians)

28. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
11
Triploblasts
(Bilaterians)

29. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Protostomes
12
Protostomes

30. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Protostomes
13
Deuterostomes

31. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Deuterostomes
14

32. Figure 33.1 Phylogeny of the Deuterostomes
!15Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

33. General/Common Features of Deuterostomes Common Ancestor
!16Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

34. General/Common Features of Deuterostomes Common Ancestor
!17Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Development
!Radial cleavage
!Blastopore becomes the anus
and mouth forms on opposite
side
!Coelom develops from
mesodermal pockets that bud
off from the gastrula cavity
!Triploblastic, coelomate animals
with internal skeletons
!Complete gut.
• There are far fewer species of
deuterostomes than protostomes.

35. Three Main Clades
!18Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Echinoderms
Hemichordates
Chordates

36. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
19
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Ambulacrarians
• Two main groups: echinoderms and hemichordates
• Have ciliated, bilaterally symmetrical larvae
• Adult hemichordates are also bilaterally
symmetrical.

37. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
19
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Ciliated
larvae
Ambulacrarians
• Two main groups: echinoderms and hemichordates
• Have ciliated, bilaterally symmetrical larvae
• Adult hemichordates are also bilaterally
symmetrical.

38. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
19
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Radial symmetry as adults,
calcified internal plates,
loss of pharyngeal slits
Ciliated
larvae
Ambulacrarians
• Two main groups: echinoderms and hemichordates
• Have ciliated, bilaterally symmetrical larvae
• Adult hemichordates are also bilaterally
symmetrical.

39. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians - Others - Xenoturbellids
20
Xenoturbellids
Xenoturbellids (two species):
wormlike organisms that feed on or
parasitize mollusks in the north
Atlantic.

40. Xenoturbella in the news
!21Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

41. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• VIDEOS
22

44. !25Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

45. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
26
Xenoturbellids

46. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
27
Xenoturbellids
Acoels
Acoels: also wormlike, live as
plankton, between grains of
sediment, or on other organisms
such as corals.

47. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
28
Xenoturbellids
Acoels
s Not clear exactly where acoels
branch in the tree

48. Figure 33.4 Highly Reduced Acoels Are Probably Relatives of the Ambulacrarians
!29Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

49. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• See http://www.nature.com/news/
2011/110209/full/470161a.html for
discussion of acoels
• http://www.latimes.com/science/
sciencenow/la-sci-sn-churro-sea-worm-
bilateria-20160205-story.html
• http://www.nature.com/nature/journal/v530/
n7588/abs/nature16545.html
30

50. Clicker
Which of the following topics would studies of
Xenoturbellid evolution be most useful for?
A. Origin of diploblasty
B. Origin of radial symmetry
C. Origin of bilateral symmetry
D. Origin of segmentation
E. Origin of blastulas
!31Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

51. Clicker
Which of the following topics would studies of
Xenoturbellid evolution be most useful for?
A. Origin of diploblasty
B. Origin of radial symmetry
C. Origin of bilateral symmetry
D. Origin of segmentation
E. Origin of blastulas
!32Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

52. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Protostomes
33
Xenoturbellids

53. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
34
Xenoturbellids
Acoels
s
Focus on Two Main
Lineages of Ambulocrarians

54. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Hemichordates
35
Xenoturbellids
Acoels
s
Focus on Hemichordates
Hemichordates

55. Hemichordates Body Plan
!36Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Saccoglossus kowalevskii
ProboscisCollarTrunk

56. Hemichordates Body Plan
!37Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Saccoglossus kowalevskii
Proboscis
Proboscis used for feeding
and locomotion and
sometimes protection

57. !38Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Saccoglossus kowalevskii
Collar
Collar contains a
stomochord similar to the
notochord of chordates
Hemichordates Body Plan

58. !39Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Saccoglossus kowalevskii
Trunk
Trunk contains pharynx
and pharyngeal gill slits
Hemichordates Body Plan

59. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
For Your Personal Enjoyment
40

60. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Group 1: Acorn worms
• Up to 2 m long, burrow in soft marine sediments
• Digestive tract is a mouth, pharynx, and intestine
• The pharynx opens to the outside via pharyngeal slits.
• Vascularized tissue around the slits is a gas exchange surface.
• Prey is captured with the large proboscis, which is covered in sticky
mucus.
41

61. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Acorn Worms
42

62. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016 43

63. Group 2: Pterobranchs
• Sedentary marine animals that live in tubes secreted by the proboscis.
• Some are solitary, others form colonies.
• The collar has one to nine pairs of arms with tentacles for prey
capture and gas exchange.
!44Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

64. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
45
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Radial symmetry as adults,
calcified internal plates,
loss of pharyngeal slits
Ciliated
larvae
Ambulacrarians
Focus on Echinoderms

65. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ambulacrarians
45
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Radial symmetry as adults,
calcified internal plates,
loss of pharyngeal slits
Ciliated
larvae
Ambulacrarians
Focus on Echinoderms
Echinoderms

66. Diversity
!46Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
~7,500 species

67. Symmetry
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Larvae
are
bilateral

68. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Echinoderm Symmetry
48

69. Body Plan
!49Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Aboral (top)
Oral (bottom)
No head or brain

70. Water Vascular System
!50Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Water enters through pores
known as madreporites
Circulates
through canals
that lead to
tube feet
Hydraulic system used for
locomotion, feeding, waste
transport, respiration

71. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Echinoderm Video
51

72. Endoskeleton
• Endoskeleton derived from mesoderm
• The endoskeleton is covered in epidermis
• The skeletal plates are connected by collagen which can be
stiff or flexible which controls body tone without muscle
!52Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

73. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Echinoderm Endoskeleton
53

74. For your personal enjoyment
!54Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

75. Crinoidea- Sea Lily’s and Feather Stars
!55Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• 600 described extant species, many more in the fossil record
• Both shallow water and deep trenches
• Oral surface in dorsal, aboral surface is ventral
• Sea Lily’s are attached to the surface by a stalk
Fossil Sea Lily’s, 330 mya
Feather Star

76. Asteroidea- Sea stars
!56Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• 1500 described species, both shallow and deep habitats
• Mostly predaceous with an evertable stomach
• Remarkable capacity for regeneration
Pycnopodia- sunflower star

77. Asteroidea- Evertable stomach
!57Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• When feeding, sea stars can extend their stomach pushing it
through very small openings
• The water vascular system is used to slowly pull muscles apart
along with specialized ‘catch collagen’

78. Asteroidea- Crown of Thorns
!58Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Among the largest sea stars, spines have neurotoxins
• Voracious predator of coral (Great Barrier Reef)
• Introduced species that is difficult to control

79. Ophiuroidea- Brittle stars and basket stars
!59Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• 1,900 described species
• Long, slender arms often with spines; fast moving
• Secretive predators, some are bioluminescent
Brittle Star Basket Star Basket Star

80. Echinoidea- Sea Urchins and Sand Dollars
!60Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• 950 described species
• Slow moving, grazers on algae (Aristrotle’s lantern)
• Protected by spines (urchins) and a calcareous test
Strongylocentrotus
Aristotle’s lantern

81. Echinoidea- Sea Urchins and California Kelp
!61Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Urchins feed on kelp (brown algae)
• Kelp forests in California harbor a great diversity of species
• If unchecked, urchins can create ‘urchin barrens’
• Sea otters prey on urchins (using tools) keeping populations in
check; they are a keystone species
Kelp forest, Monterey Bay

82. Holothuroidea- Sea Cucumbers
!62Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• 1,200 described species, scavengers and filter feeders
• Soft-bodied, secondary bilateral symmetry*
• Catch collagen allows them squeeze into tight places
• Unique defense (evisceration), some are toxic

84. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Chordates
64
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Radial symmetry as adults,
calcified internal plates,
loss of pharyngeal slits
Ciliated
larvae
Ambulacrarians
Focus on Chordates

85. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Deuterostomes
65

86. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Deuterostomes
65

87. Chordate Derived Traits Most Apparent in Juveniles
!66Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

88. Notochord
!67Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Notochord is a dorsal supporting rod.
• Core of large cells with fluid-filled vacuoles, making it rigid but
flexible.
• In tunicates it is lost during metamorphosis to the adult stage.
• In vertebrates it is replaced by skeletal structures.

89. Dorsal hollow nerve cord
!68Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Formed by an embryonic folding of the ectoderm
• Develops to form the central nervous system in vertebrates

90. Post Anal Tail
!69Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Extension of the body past the anal opening
• In some species (e.g., humans) most visible in embryos
• The combination of postanal tail, notochord, and muscles
provides propulsion

91. Pharyngeal Slits
!70Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• The pharynx is a muscular organ that brings water in through
the mouth (via cilia) which then passes through a series of
openings to the outside (slits).
• Ancestral pharyngeal slits present at some developmental
stage; often lost or modified in adults.
• Supported by pharyngeal arches.

92. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Clicker
71
Why are pharyngeal slits NOT considered a
synapomorphy of chordates?
A. They occur in other deuterostomes
B. They are lost in some chordates
C. They are modified into gills in vertebrates
D. They only occur in the embryo of some chordates

93. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Clicker
72
Why are pharyngeal slits NOT considered a
synapomorphy of chordates?
A. They occur in other deuterostomes
B. They are lost in some chordates
C. They are modified into gills in vertebrates
D. They only occur in the embryo of some chordates

94. Figure 33.1 Phylogeny of the Deuterostomes
!73Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016

95. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Chordates
74
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Radial symmetry as adults,
calcified internal plates,
loss of pharyngeal slits
Ciliated
larvae
Ambulacrarians
Focus on Chordates

96. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Chordates
75
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Radial symmetry as adults,
calcified internal plates,
loss of pharyngeal slits
Ciliated
larvae
Ambulacrarians
Three Major Groups
*Lancelets
*Tunicates
*Vertebrates

97. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Lancelets (aka Cephalochordates)
76
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Radial symmetry as adults,
calcified internal plates,
loss of pharyngeal slits
Ciliated
larvae
Ambulacrarians
Focus on Lancelets

98. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016 77
Branchiostoma lanceolatum
Gut
TailAnus
Dorsal hollow
nerve cord
NotochordPharyngeal
slits
Lancelet Has Key Chordate Features

99. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016 78
Branchiostoma lanceolatum
TailAnus
Dorsal hollow
nerve cord
NotochordPharyngeal
slits
Lancelet Features
• Lancelets (aka amphioxus) are very small, less than 5 cm.
• Notochord is retained throughout life.
• Burrow in sand with head protruding; also swim.
• Pharynx is enlarged to form a pharyngeal basket for filtering prey from the water.
• Fertilization takes place in the water.
• Segmented body muscles

100. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Lancelet development
79

101. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Tunicates
80
Chordates
Common
ancestor
(bilaterally
symmetrical,
pharyngeal
slits
present)
Echinoderms
Hemichordates
Lancelets
Tunicates
VertebratesVertebral column, anterior skull,
large brain, ventral heart
Notochord,
dorsal hollow
nerve cord,
post-anal tail
Radial symmetry as adults,
calcified internal plates,
loss of pharyngeal slits
Ciliated
larvae
Ambulacrarians
Focus on Tunicates

102. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Adult Tunicates
81
• Tunicates (sea squirts or ascidians, thaliaceans, and
larvaceans):
• Sea squirts form colonies by budding from a single founder.
Colonies may be meters across.
• Adult body is baglike and enclosed in a “tunic” of proteins
and complex polysaccharides secreted by the epidermis.

103. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Adult Tunicates
82
• Solitary tunicates seem to lack all of the synapomorphies of
chordates?
• No dorsal hollow nerve cord, no notochord, no postanal tail

104. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Adult Tunicates
83
• Solitary tunicates seem to lack all of the synapomorphies of
chordates?
• No dorsal hollow nerve cord, no notochord, no postanal tail
HOW ARE THESE CHORDATES?

105. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Juvenile Tunicates
84
Ascidian tunicate larva
• Sea squirt larvae have pharyngeal slits, a hollow nerve cord,
and notochord in the tail region.
• The swimming, tadpolelike larvae suggest a relationship
between tunicates and vertebrates.
• Larvacean tunicates do not undergo the metamorphosis and
retain all of the chordate features.
Larvacean tunicates

106. Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Vertebrates
85