Aim: Who were the first animals to evolve? Date: October 24, 2013 Catalyst: Throwback Thursday! 1. What is the difference between vascular and non-vascular plants? 2. What are three major adaptations of plants for terrestrial life? 3. How do fungi get energy? 4. What are mycorrhizae?
Reminders Practice your vocabulary!!! Stay up to date with readings. They relate to what we do in class each day. See me at lunch any day of the week, or after 8th period Tues, Weds, and Friday for extra help. Email nburley@northsidechs.org if necessary.
Reminders Develop success from failures. Discouragement and failure are two of the surest stepping stones to success.! -Dale Carnegie
Question of the Day What is true of natural selection? A) Natural selection is a random process. B) Natural selection creates beneficial mutations. C) The only way to eliminate harmful mutations is through natural selection. D) Mutations occur at random; natural selection can preserve and distribute beneficial mutations. E) Mutations occur when directed by the good of the species; natural selection edits out harmful mutations and causes populations to adapt to the beneficial mutations.
Agenda QOTD Our place in the timeline of Life on Earth The Rise of Multicellular animals Early Animal Groups in the Pre-Cambrian Ediacaran The Cambrian Explosion
Where, or when, are we? Thus far on Earth, the following have evolved: Multicellular life - 2.1 billion years ago Eukaryotes - 1.5 billion years ago
First animals - 770 million years ago First terrestrial plants - 470 million years ago
Multicellularity Protists were first to become multicellular Protists - eukaryote that is not plant, animal, or fungus Protists formed colonies, joined together using proteins Template for animals, especially sponges
Early animals of the Ediacaran
Early animals of the Ediacaran Fossils and DNA evidence point to sponges, mollusks, and cnidarians as the earliest animals
Sponges Monophyletic - group that contains ancestor and descendants Filter feeders - filter food from water by passing through body Lack tissues Do have varied cells Choanocytes - engulf bacteria and other food particles. Similar to protists Amoebocytes - take food from choanocytes, digest, and carry nutrients
Sponges
Sponges
Cnidarians Have tissues Jellyfish, sea anemones, hydrozoans Sac with a gastrovascular cavity - central digestive compartment (mouth and anus same) Carnivores that use tentacles to pass prey into cavity, enzymes break down, and nutrients are absorbed Nerve net - no central nervous system, sense stimuli from all directions
Cnidarians
The Cambrian
Cambrian Explosion 560 million years ago Bilaterian - complete digestive tract, two-sided symmetrical form First arthropods - segmented bilaterians, with joints (insects, spiders, crabs) First chordates - animals that at some point in life have a notochord First echinoderms - radially symmetrical body with skeleton
Cambrian Explosion Predation began, defense and predation mechanisms seen in fossils As cambrian creatures evolve, ediacaran disappear Why might this happen?
Theories 1. Introduction of new traits caused ediacarans to be outcompeted by cambrian organisms 2. Increase in atmospheric oxygen allowed larger bodies and higher metabolic rates to thrive, could hurt other animals 3. Hox genes and other changes allowed evolution of new body forms
Cambrian Explosion Revision of theory showed that some eukaryotes became large Spines began to develop on eukaryotes Natural selection favored increased size and defense mechanism Early bilaterians diversified during cambrian
Sponges are most accurately described as A) marine predators. B) chemoautrophs. C) freshwater scavengers. D) filter feeders. E) aquatic predators.
Red Light Choose one of the following concepts. How does this concept apply to today s lesson?! 1.B Organisms are linked by lines of descent from common ancestry. 1.C Life continues to evolve within a changing environment.