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Invertebrates & Chordates: Evolution, Characteristics, & Innovations - Prof. Ray Spear, Study notes of Biology

State University of New York at Geneseo (SUNY)Biology
Prof. Ray Spear

An insightful exploration into the world of invertebrates and chordates, focusing on their evolution, key innovations, and distinct characteristics. Topics covered include the segmented body plan of arthropods, the advantages and challenges of an exoskeleton, the role of an exoskeleton in the move to a terrestrial environment, and the unique features of echinoderms and chordates. Students will also find information on insect flight, the deuterostome phyla, and the anatomy of sea stars.

Typology: Study notes

2011/2012

Uploaded on 05/13/2012

erikaschoene
erikaschoene 🇺🇸

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1/26/2012
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Invertebrates & Chordates
Announcements
•Quiz will open online Thursday @1pm, close
Friday @ 12noon
•PRS “problems”
Phylum Arthropoda – the real rulers of
the earth
•Diversity of arthropods
is unmatched by any
other group (make up
95% of known animal
sp.)
Evolution of Segmented Body Plan
•Early arthropods (eg.
trilobites) showed little
variation from segment
to segment
•As arthropods evolved,
segments fused, &
appendages became
more specialized
•Appendages of some
living arthropods are
modified for many
different functions
Key Innovations of Arthropod Body
Plan
•Exoskeleton
•Jointed limbs
•Segmented body
–Head (strong
cephalization)
–Thorax ( jointed
limbs & wings
attachments)
–Abdomen
Exoskeleton advantages &
challenges
•ADVANTAGES:
–a protective feature
–important for attachment of muscles
•rapid movement and precise control over their movement
•CHALLENGES:
–Growth = molting
•Loss of protection
•Energetically costly
pf3
pf4
pf5

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Download Invertebrates & Chordates: Evolution, Characteristics, & Innovations - Prof. Ray Spear and more Study notes Biology in PDF only on Docsity!

Invertebrates & Chordates

Announcements

  • Quiz will open online Thursday @1pm, close Friday @ 12noon
  • PRS “problems”

Phylum Arthropoda – the real rulers of

the earth

  • Diversity of arthropods is unmatched by any other group (make up 95% of known animal sp.)

Evolution of Segmented Body Plan

  • Early arthropods (eg. trilobites) showed little variation from segment to segment
  • As arthropods evolved, segments fused, & appendages became more specialized
  • Appendages of some living arthropods are modified for many different functions

Key Innovations of Arthropod Body

Plan

  • Exoskeleton
  • Jointed limbs
  • Segmented body
    • Head (strong cephalization)
    • Thorax ( jointed limbs & wings attachments)
    • Abdomen

Exoskeleton advantages &

challenges

• ADVANTAGES:

  • a protective feature
  • important for attachment of muscles
    • rapid movement and precise control over their movement
  • CHALLENGES:
  • Growth = molting
  • Loss of protection
  • Energetically costly
  • How did an exoskeleton help in the move to a terrestrial environment (over evolutionary time)? - in the sea, for protection & anchorage for muscles - on land also for protecting against dessication - also provides structural support for the body on land (buoyancy lost when they left the sea)

Arthropod Characteristics

  • Arthropods have an open circulatory system in which fluid called hemolymph is circulated into the spaces surrounding the tissues and organs
  • A variety of organs specialized for gas exchange have evolved in arthropods

Insects as Model Arthropods

  • Insects and their relatives, have more species than all other forms of life combined
  • They live in almost every terrestrial habitat and in fresh water
  • The internal anatomy includes several complex organ systems

INSECT BODY PLAN

FIG 33- 35 Tracheal system – external openings = spiracles Excretion of waste – Malpighian tubules Nervous system – complex w/ ganglia & ventral double nerve cord Specialized appendages & wings

What characteristic is shared by BOTH

cnidarians and flatworms?

  • A. Dorsoventrally flattened bodies
  • B. Specialized excretory cells
  • C. Radial symmetry
  • D. A digestive system with a single opening
  • E. Both A and D Which of the following is probably MOST responsible for the incredible diversification of insects on land?
  • A. Segmentation
  • B. Antennae
  • C. Tracheal system
  • D. Bilateral symmetry
  • E. Flight

Figure 33.38 Anatomy of a sea star

  • Sea stars, have multiple arms radiating from a central disk - undersurfaces of each arm bears tube feet, that act like a suction disks
  • Sea urchins & sand dollars have no arms but have five rows of tube feet
  • Water Vascular System is common to all groups - Used for locomotion, food/waste transport & respiration

Echinoderm Video

  • http://www.youtube.com/watch?v=H2EEoR_X lYg Echinoderms like the sea urchins/cucumbers in the video have no head, no CNS, or other characteristics we usually associate active consumers, yet they are very successful. What would you conclude about this group? - A. Even very primitive animals can survive today - B. There is more than one way to be a successful consumer - C. An organism that is well adapted to its environment will be successful - D. I can’t make any conclusions about this group from this information.

Deuterostome Phyla

  • Phylum Echinodermata
  • Phylum Chordata

Chordata

Phylum Chordata = 2 subphyla of invertebrates plus hagfishes and vertebrates Chordates share features of embryonic development with echinoderms All chordates share a set of derived characters Some species have some of these traits only during embryonic development

Chordate Characters: Derived characters in

ALL Chordates

Notochord

  • semi-flexible rod running along the length of the animal
  • In chordates w/o bone, muscles work against the notochord to move the animal slits or clefts^ Pharyngeal Mouth Brain Dorsal, hollow nerve cord Notochord Muscle segments post^ Muscular,-anal tail^ Anus Post-anal Tail
  • extension of the notochord & nerve cord past the anus
  • lost in adult stages of many chordates

Chordate Characters

  • Pharyngeal slits = openings between the pharynx (throat) and the outside. - Filter food particles, hold gills - Supported by gill arches – modified in many vertebrates
  • Dorsal Nerve Cord
    • hollow, w/ pairs of nerves branching and running to the muscles
    • anterior (forward) end of the nerve cord is often enlarged into a brain. slits or clefts^ Pharyngeal Mouth Brain Dorsal, hollow nerve cord Notochord Muscle segments post^ Muscular,-anal tail^ Anus An hypothesis for chordate evolution: key characteristics in evolution Notochord Vertebral Column Jaws Amniotic Egg Lungs Legs