Porifera: Characteristics and Systems
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Questions and Answers

Which of the following scenarios best illustrates the characteristic of 'replication' in living organisms?

  • A plant bending towards sunlight to maximize photosynthesis.
  • Enzymes catalyzing a biochemical reaction in a cell.
  • A bear hibernating during the winter months to conserve energy.
  • Bacteria dividing to form two identical daughter cells. (correct)

A scientist discovers a new organism in a remote environment. After analyzing its properties, which observation would provide the strongest evidence that the organism is alive?

  • The organism contains complex organic molecules.
  • The organism responds to external stimuli.
  • The organism maintains a stable internal temperature.
  • The organism is capable of self-replication and adaptation over generations. (correct)

Consider a population of bacteria exposed to an antibiotic. Initially, most bacteria are susceptible, but over time, a greater proportion becomes resistant. Which characteristic of life is primarily responsible for this change?

  • Information processing
  • Energy utilization
  • Evolution (correct)
  • Cellular organization

A researcher is studying a newly discovered structure. Which of the following findings would lead to the conclusion that it is a living cell?

<p>All of the above. (D)</p> Signup and view all the answers

Which of the following examples illustrates how living organisms utilize 'information'?

<p>A sunflower turning its head to follow the sun's movement across the sky. (A)</p> Signup and view all the answers

Flashcards

Energy

The capacity to do work, powering life processes.

Cells

Membrane-bound units; the basic structural and functional units of life.

Information

Hereditary or environmental signals that can cause a response.

Replication

The production of new individuals; reproduction.

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Evolution

Change in the characteristics of a population over time.

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Study Notes

  • Five characteristics of life are energy, cells, information, replication, and evolution.
  • Multicellularity distinguishes animals.

Sponges (Porifera)

  • Main features include the aquiferous system, pores, sessile adults, and motile larvae.
  • Expanded gene flow happens because larvae are motile.
  • The aquiferous system involves water flowing through pores to the atrium, then out the osculum (opening).
  • Choanocytes create currents that bring water through ostia into the spongocoel and out through the osculum.
  • Choanocytes (collar cells) trap food particles and amoebocytes distribute nutrients.
  • The skeletal framework is made of spongin or spicules.
  • Spongin is soft, mostly collagen, strong, but flexible.
  • Spicules are hard, strong, and inflexibile.
  • Spicules protect sponges from predation, made of calcium carbonate or silica.
  • Asexual reproduction includes gemmules, clusters of cells that survive tough conditions.
  • Sexual reproduction occurs when sperm are released into the water and fertilization occurs inside another sponge.
  • Carnivorous sponges trap small prey using modified filaments instead of filter feeding.
  • Glass sponges have a special structure that forms silica spicules with a lattice framework.
  • Encrusting sponges are flattened sponges that grow over rocks.

Cnidarians

  • Main are mostly marine, range from microscopic to very large, have a simple body plan, and radial symmetry.
  • Cnidocytes are unique to cnidarians.
  • Lack a head, respiratory system, and circulatory system.
  • Two main types are polyps and medusa.
  • Tentacles, mouth, ectoderm, mesoglea, endoderm, and gastrovascular cavity are features of both types.
  • Polyps have a pedal disc for attachment and a column as the main cylindrical body.
  • Colonial polyps are groups of genetically identical polyps connected by shared tissue, forming a single organism like corals or siphonophores such as the Portuguese man o' war.
  • Cnidocytes are used for prey capture, defense, locomotion, and attachment.
  • Reproduction can be sexual and asexual.
  • Asexual reproduction happens through budding where small medusae grow from the parent and fission where the parent splits.
  • During the sexual stage, adult medusae produce gametes, fertilization occurs, a zygote forms, and develops into planula larva, which develops into a polyp.
  • During the asexual stage, the polyp undergoes strobilation to produce multiple stacked disc-like segments, which break off as ephyrae, finally growing into medusae and restarting the cycle.
  • Four main groups include hydrozoans, anemones & corals & sea pens, box jellyfish, and true jellyfish.
  • Hydrozoans include Hydra and By-the-wind Sailor.
  • By-the-wind Sailors have a hyroid colony, eat plankton, are harmless to humans, and have photosynthetic symbionts.
  • The Portuguese Man O' War is a siphonophore made up of a colony of genetically identical zooids.
  • Anemones, corals, and sea pens engage in fish symbioses.
  • Types: soft corals, sea fans, pygmy seahorses, brittlestars, tube anemones, stony corals.
  • The box jellyfish includes sea wasps and irukandji, theyprey upon plankton, are very deadly to humans and have eyes with lenses.
  • Moon jellyfish circles are the gonads.
  • Lion's mane jellyfish are found in the North Atlantic, are colorful, and have very long tentacles.
  • Crabs live in the folds of giant jellyfish.
  • The cannonball and Bay nettle jellyfish are northern.

Comb Jellies (Ctenophores)

  • They lack cnidocytes and cannot sting.
  • Most are free swimming which included roughly 300 species.
  • Are one of the oldest lineages of animals.
  • Have biradial symmetry.
  • Use combs to move through the water, similar to cilia.
  • Refract light using cilia (combs), has a rainbow effect
  • The body plan includes a mouth, stomach, and anal pores.
  • Have two tentacles, sometimes retractable, and sticky cells to capture prey.
  • They are soft bodied gelatinous animals.
  • Two types are the sea walnut (elongated shape) and the sea gooseberry.

Placozoa

  • They are amoeba-like, have an outer epithelium, cilia, and shiny spheres in the dorsal epithelium.

Flatworms (Platyhelminthes)

  • 4 main groups: Free-living flatworms, tapeworms, flukes and fish ectoparasites.
  • Planarians are mostly hermaphrodites.
  • Parasitic species (flukes and tapeworms) have complex life cycles with incredible powers of regeneration.
  • Free-living flatworms are small, inconspicuous, mostly benthic, and most are carnivorous.
  • Bright worm colors indicate that they are poisonous.
  • Dog tapeworms have tapeworm proglottids, which contain eggs for reproduction breaking off and existing the body through feces.
  • Pork and beef tapeworms cause taeniasis.
  • Schistosomiasis doesn't occur in the US.
  • The adult form of the Chinese liver fluke lives in the liver, lays eggs, and spreads through fecal matter moving digestive tract.

Segmented Worms (Annelids)

  • Bristle worms general include wandering predators or are sedentary in sediment.
  • Errant (wandering) move look for food.
  • Have well developed parapodia that appears like mini legs with bristles that assist in movement.
  • They live in the ocean and drifting larval stages add to genetic diversity.

Types of Bristle Worms

  • Rag Worms like shallow and sandy environments, are carnivorous, and can bite
  • Scale Worms look as though they have scales but are actually called elytra and are active hunters in intertidal to deep sea.
  • Spaghetti Worms still have bristles and use them to anchor and live in rocky shores and coral reefs.
  • Sea Mouse acts as scavengers and predators and are found in Mediterranean and Atlantic oceans.
  • Feather duster worms have parchment like tube and are subtidal and global with Feathery radioles to catch organic matter, they filter feed.
  • Parchment tube worm build a paper like tube in the sediment and crabs live in their tubes.
  • Carolus Linnaeus created the binomial nomenclature in 1735.
  • The two part name refers to genus and species with individuals that regularly breed together as the same species, or individuals whose characteristics are distinct from those of other species.
  • Earthworms have more than 6000 species and are terrestrial and aquatic with hydrostatic skeletons.

Ice Worms

  • They spend their entire lives in glaciers, don't freeze due to sugars that act as antifreeze in their blood and prefer to avoid sun and operate at low temps

Leeches

  • There are more than 500 species of leeches including the Turtle leech and NA (North American) medicinal leech
  • They have suckers on front and back (anterior & posterior)
  • They can be bloodsucking or predatory
  • Lack parapodia and bristles
  • Medicinal Leeches (hirudo medicinalis) have 2 main medical uses; it keeps blood in liquid form via hirudin and increases blood flow to infected area, although it includes risks such as anaphylaxis and infection

Nematodes (Roundworms)

  • Include about 25,000 species
  • They are abundant animals in the ocean, freshwater, and land.
  • Wide spread animals
  • Some are parasites
  • Are unsegmented and dimorphic
  • Reproduction internally fertilizes with internal or external development of eggs

Notable Nematodes

  • Hookworms burrow into human skin (usually bottom of foot) to get blood circulation.
  • Soil Nematode: Simple body plan, east to grow, transparent and freeze tolerant
  • Human Whipworm:1 host parasite whose eggs which look like little footballs can be found in coprolites from 7,100 BC and do not multiply within the host.
  • Trichinella causes trichinosis in which adults and larvae infect almost any mammal and are transmitted through predators (pigs, bears, rodents etc.).

Guinea Worm

  • They are transmitted when people accidentally drink crustaceons that they infect and then move under the skin to then burrow out of the body
  • WHO removed this type of worm

Giant Intestinal Roundworm

  • Mild infections causes no symptoms with Major infections cause obstructions, malnourishment, damage organs of the intenstines

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Description

Explore the characteristics of life as seen in Porifera (sponges), including their aquiferous system, sessile adults, and motile larvae. Learn about choanocytes, amoebocytes, and the skeletal structures made of spongin and spicules. Understand both asexual and sexual reproduction in sponges.

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