Insecta and Deuterostomes

INSECTA…AND DEUTEROSTOMES INSECTA—CLADE ARTHROPODA 1. Insects have 3 major adaptations that are important for their success. What are those, and how do these adaptations make them successful?

1. Flight—get to exploit new resources, etc.

2. Specialized mouth parts—get to eat new things (exploit new resources), etc. 3. Metamorphosis—adults and offspring do not need to compete because the 2 life stages have very different habits 2. How do insects impact ecology and our economy? They pollinate plants, they’re vectors for disease, compete with humans for food, and we’ve created dangerous poisons to kill them on crops (insects are becoming resistant!)…

DEUTEROSTOMES 3. Echinodermata includes species like starfish, sea urchins, sand dollars, etc. and is considered bilaterally symmetric. A starfish isn’t bilaterally symmetric!! How are they considered bilateral? The larval forms of echinoderms are bilaterally symmetric; adults are not. 4. All chordates have what 4 characteristics? What are their functions? Do these 4 characters persist throughout their life cycles? No! (Many of these characters are lost during development to the adult.) 1. Notochord—used for muscle attachment

2. Dorsal hollow nerve cord—develops into the central nervous system (brain and spinal cord) 3. Pharyngeal slits—used for water passage and gas exchange; also can develop into other things like jaws or inner ear parts or gills 4. Post-anal tail—(function not pertinent because rarely persists into adulthood but…) holds skeletal elements and muscles…

5. True or False: The majority of species on Earth are found in the subphylum Vertebrata. False! Vertebrates are less than 5% of species!!! 6. What characteristics do vertebrates have that not all chordates do?

1. Cephalization (skulls)

2. Vertebral column enclosing the nerve cord (replaces notochord in development) 3. Endoskeletons grow within vertebrates

4. Closed circulatory systems 7. Certain vertebrates produce an amniotic egg. How is it different than other eggs? Why is it an important adaptation? It has “extraembryonic” membranes, meaning an extra layer (the shell). It allows embryonic development to occur on land so they don’t dry out! What three things do amniotic eggs have, and what are they used for?

1. Membranes—gas exchange, waste storage and nutrient transfer

2. Fluid—protects developing embryo

3. Shell—prevents desiccation, protects embryo

8. What clade are birds found in? Reptilia! (Counter-intuitive, perhaps?) What important adaptation do birds have that others don’t, and how is it beneficial? Birds have flight! It’s advantageous to exploitation of flying insects, to escape from predators and for long-distant migration.

9. What 4 characteristics do mammals share? Do all vertebrates have these 4? No—not all vertebrates are mammals… 1. Mammary glands

2. Hair

3. Diaphragm

4. Specialized teeth

10. We discussed different groups of mammals. What is the important distinction between these groups? Not all mammals…have embryonic development completely within the mothers! (Also, not all mammals have live birth!)

11. True or False: Humans evolved from chimpanzees, based on the fact that only 1% of our DNA sequence differs from that of chimps. False—the fact is true, but humans did NOT evolve from chimpanzees, they just share a common ancestor with them. 