To start things off in class today, we turned in UP pgs. 35-36 and we got UP pg 37 stamped.
The rest of class we finished up the animal notes. Here they are:
The Evolution of Multicellularity (We might of done this before but I can't remember exactly, so I will put them in just in case)
- Animals probably evolved from a colonial, flagellated protist that lived in Precambrian seas.
- By the late Precambrian, animals were already diverse.
- At the beginning of the Cambrian period, animal diversity exploded.
- Over about 10 million years ago, all the major animal body plans existing today evolved.
Early Animals and the Cambrian Explosion
- In the last half-billion years, animal evolution has mainly generated new variations of old "Designs" that originated in the Cambrian Seas
- This "explosion of diversity" in the Cambrian period marked the fossil record as the beginning of the Paleozoic era.
- The "explosion" could be due to increasingly complex predator-prey relationships that led to diverse adaptations for feeding, motility, and protection. (ex: shells or hard exoskeleton evolved vs. earlier soft-bodies.)
- Or, the explosion could be due to variation in how and when, and where genes that control the development of animal form are exposed. (ex: placement of body parts in embryos can produce major differences int he phyla)
- To reconstruct the evolutionary history of animal phyla, researchers must depend on clues from comparative anatomy and embryology
- This diagram represents one set of hypotheses about evolutionary relationships among nine major animal phyla.
- Radial symmetry--animals that are arranged around a central axis. A single cut through the middle of the organism in any direction should produce two equal halves (kind of like a pizza)
- Bilateral symmetry--A single longitudinal cut only in one direction will produce two equal halves.
- A fluid filled space separating the digestive tract from the outer body wall. (Body cavity=coelom or gut)
- Its fluid cushions the suspended organs to prevent internal injury.
- It enables internal organs to grow and move independently of the outer body wall; makes exercise not harmful to internal organs.
- In soft-bodied animals, it functions as a hydrostatic skeleton against which muscles can work (ex: for burrowing)
- Ex: Flatworms lack a body cavity=acoelomate
- Ex: Roundworms have a body cavity partially lined by mesoderm (middle layer tissue)=pseudocoelomate
- Ex: Earthworms have a body cavity completely lined by mesoderm=coelomate
Details of Embryonic Development
- Of the animals with a true coelom, there are 2 branches:
- Branch 1: mollusks, annelids, arthropods: mouth develops first in embryo=Protosomes
- Branch 2: echinoderms and chordates: anus develops first in embryo=Deuterostomes
Animalia Kingdom- 8 Major Invertebrate Phyla:
- Invertebrates, animals w/o backbones, represent more than 95% animal kingdom!!
- Sponges are sessile (non-moving)
- Sponges are the simplest animals, probably evolved very early from colonial protists.
- Range in height from about 1 cm to 2 meters
- Have no nerves or muscles (This explains why SpongeBob is so weak ;D), and consist of about 9,000 species
- About 100 species lives in fresh water and the rest are marine.
- The body of a sponge resembles a sac perforated with holes.
Sponges Feeding Method:
- Most sponges feed by collecting bacteria from the water which streams through their porous bodies (filter feeding)
- Flagellated cells called choanocytes trap bacteria in mucus and then engulf the food by phagocytosis
- Cells called amoebocytes pick up food from the choanocytes, digest it, and carry nutrients to other cells
- Cnidarians show radial symmetry.
- Are carnivores, with cnidocytes (stinging cells) on their tentacles.
- Consist of more than 10,000 mostly marine species
- Have a body plann that is a sac with a central digestive compartment, the gastrovascular cavity. This cavity functions as a mouth and an anus.
- Two body forms: the sessile polyp attaches to a substrate, and the free-floating medusa.
3. Phylum Platyhelminthes--Flat Worms--Tapeworms, Flukes, and Planaria
- Flatworms are the simplest bilateral animals.
- Range from about i mm to 20 m in length.
- Live in marine, freshwater, and damp terrestrial habitats.
- Include many parasitic species including flukes and tapeworms
- Tapeworms have a ribbon-like body which can be up to 20 m long in humans
- Lack a digestive tract, so they absorb partially digested food from the intestines of their host.
- Humans can become infected with tapeworms by eating undercooked food.
4. Phylum Nematoda-Round Worms
- Roundworms get their common name from the cylindrical bodies tapered at both ends.
- Roundworms are among the most diverse and widespread animals.
- Roundworms consist of about 90,000 known species (10x more actually exist!)
- Range in length form 1mm to 1m.
- Live in most aquatic habitats , in wet soil, and as parasites in the body fluids and tissues of plants and animals
- Exhibit a complete digestive tract with a mouth and anus
- Have a body cavity: pseudocoelom
- Humans host at least 50 parasitic species including pinworms, hookworms, and the parasite which causes trichinosis
5. Phylum Annelida--Segmented Worms--Earthworms, Polychaetes, and Leeches
- Annelids are worms with body segmentation, the division of the body along its length into a series of repeated parts.
- Annelids consist of about 15,000 species
- Range in length from 1mm to 3m long
- Live int he sea, most freshwater habitats, and damp soil
- The three major classes of annelids are stated in the title.
- Farmers value the earthworm because they eat their way through the soil, extracting nutrients, tilling the soil, and producing nutrients which improve the texture of the soil
- Polychaetes are marine; crawl or burrow in the seafloor
- Polychaetes have segmented appendages and hard bristles that help the worm move. The appendages also increase the animals surface are for gas exchange and elimination of metabolic wastes
- Leeches include medicine, until the 20th century for blood-letting.
- Leeches are currently used as a source or anticoagulant and to help relieve swelling in reattached fingers and toes
6. Phylum Mollusca-Snails, Slugs, Clams, Octopuses, and Squid
- Mollusks are soft-bodied animals
- Are usually protected by a hard shell (Although slugs, squids, and octopuses have either reduced shells, most of which are internal or none at all.)
- Often feed by using a straplike rasping organ called a radula to scrape up food.
- Consist of about 150,000 species that are primarily marine, although some inhabit fresh water (snails, clams) and some live on land (snails, slugs)
- All Mollusks have a similar body plan with three main parts: a muscular foot, usually used for movement, a visceral mass containing most of the internal organs, and a fold of tissue called the mantle that drapes over the visceral mass, and secretes the shell if one is present.
- There are three major types of mollusks:
- Gastropods which include snails and slugs.
- Bivalves include clams, oysters, and mussels
- Cephalopods which include squids and octopuses
7. Phylum Arthropoda--Crustaceans, Millipedes, Centipedes, and Insects
- Arthropods are named for their jointed appendages
- Number more then a billion billion (1,000,000,000,000,000,000) living individuals
- Include more than 1 billion identified species (two out of three) and are represented in nearly all habitats of the biosphere
- Arthropods are the most successful of all animal phyla as far as species diversity, distribution, and sheer numbers
- Arthropods are the most segmented animals with appendages that have become specialized for a great variety of functios
- Sensory reception
- The body of an arthropod covered by an exoskeleton
- Must occasionally shed it and secrete a larger one-molting
- Temporarily vulnerable to predators
- Arachnids: include scorpions, spiders, ticks, and mites
- Crustaceans: include crabs, lobsters, crayfish, shrimps, and barnacles
- Millipedes: eat decaying plant matter, have 2 pairs of short legs per body segments and Centipedes: paralyze prey (cockroaches & flies) and have one pair of long legs per body segment
- Insects: including bees, grasshoppers, ants, termites, and cockroaches. Outnumber all other forms of life combined
8. Phylum Echinodermata--Spiny Skin--Starfish, Sand Dollars, & Sea Cucumbers
- Echinoderms are named for their spiny skin
- All echinoderms are marine
- Most are sessile or slow moving
- Lack body segments
- Have an endoskeleton constructed from hard plates just beneath the skin.
- Have a water-vascular system, a network of water filled canals that circulate water throughout the echinoderm's body, facilitating gas exchange and waste disposal
- Have tube feet connected to the water-vascular system for movement
- Larvae form=bilateral symmetry
- Adult form=radial symmetry
- Share an evolutionary branch with chordates
That is all for the notes!
HW: Study Animal Notes, Nature due March 2, isopod research (if you want to), earthworm lab tomorrow
Have a good evening and the next scribe is Jack