Invertebrates and Flatworms Flashcards

Invertebrates

• The lecture will cover the animal kingdom, starting with invertebrates and then moving to vertebrates.

• Invertebrates lack a backbone.

• Vertebrates (mammals, cats, dogs, etc.) have a backbone.

• Most animals are invertebrates.

• Invertebrates make up about 95% of animal species, but the exact number isn't crucial.

Sponges (Porifera)

• Structural identification will be tested in the lab, not in the lecture exam.

• You need to know the function of structures discussed in the lecture, but not identify the structures.

• Most sponges are marine, but some are found in freshwater.

• Sponges are hermaphroditic, possessing both male and female reproductive structures.

• Sponges lack true tissues (groups of cells with a common function).

• If a sponge is blended into individual cells, those cells can reform into a sponge.

• Sponges lack organs and have only one germ layer.

• Sponges are sessile (immobile) except during their larval stage.

• Sponges feed via suspension feeding or filter feeding, trapping food particles from water passing through their bodies.

• Two main types of cells exist in sponges:

  • Choanocytes (collar cells): These have flagella that beat to create water flow into the sponge, bringing in food and nutrients. Their main job is to beat their flagella and cause water to flow.

  • Amoebocytes: These are like stem cells, capable of transforming into any cell type the sponge needs, including egg cells. They can also crawl about and feed. They mainly crawl about feeding.

• Choanocytes trap food, which is picked up by amoebocytes. Amoebocytes then break down the food and share some with the collar cells.

• During sexual reproduction, choanocytes turn into sperm, while amoebocytes give rise to eggs.

• Amoebocytes produce spicules, which provide structural support.

• Sponges reproduce both sexually and asexually.

• Lunar cycles or water temperature may trigger sexual reproduction in sponges.

  • Sponges release sperm all at once over large distances.

  • After sperm release, eggs are released, timed to lunar cycles or temperature.

• Asexual reproduction occurs in two ways:

  • Gemmules: Sponges produce gemmules, packets containing amoebocytes, which can grow into new sponges.

  • Fragmentation: Pieces of a sponge that break off can grow into new sponges (rare).

• Structures and Functions:

  • Osculum: The opening where filtered water exits the sponge.

  • Mesenchyme: A jelly-like material that binds the sponge's parts together, similar to connective tissue.

  • Spicules: Hard materials (silica/glass, calcium carbonate/rock, or protein/collagen) that provide structural support and potentially anti-predatory function.

    • Sponges used for cleaning the body use protein/collagen spicules to be flexible and soft.

• Sponges in the Caribbean produce spongothymidine, a molecule resembling thymine (a DNA base).

  • Spongothymidine may fight viral infections.

  • Viruses may use spongothymidine instead of thymine to make its DNA, then the viral DNA will not work.

  • This led to the creation of AZT, an anti-HIV drug.

    • AZT is a synthetic drug that looks like a nucleotide with the base thymine.

    • If HIV uses AZT instead of thymine, the virus cannot reproduce.

    • Drugs like AZT are called nucleoside inhibitors, which are fake nucleotides.

    • In AZT, ammonia is attached to the third carbon preventing attachment of a new nucleotide.

Cnidarians ( অন্তর্ভুক্ত Jellyfish, Corals এবং Anemones)

• Cnidarians include jellyfish, corals, and anemones.

• Cnidarians are the first group of animals with true tissues (Eumetazoa).

• General characteristics of cnidarians:

  • Radial symmetry.

  • Hydrostatic skeleton: Water supports the body instead of bones.

  • Two forms: Polyp (sessile) and Medusa (motile).

  • Diploblastic: Two germ layers.

  • Nerve net: Primitive nervous tissue allowing response to the environment.

  • Nematocysts: Harpoon-like structures on tentacles with paralyzing toxins for defense and prey capture.

• Cnidarians use tentacles to pull in prey, which goes into the gastrovascular cavity where enzymes break it down.

• Nematocysts contain toxin; contact triggers firing, paralyzing prey, which is then digested in the gastrovascular cavity.

• The nerve net is a primitive nervous system where neurons are not concentrated in a head but distributed all over.

• Cnidarians have an incomplete digestive system with only one opening for both mouth and anus.

Classification of Cnidarians

• Four classes: Hydrozoa, Scyphozoa, Cubozoa, Anthozoa.

Hydrozoa

• Mostly small and marine, with predatory feeding habits.

• Alternate between polyp and medusa stages.

• Medusa stage is used for sexual reproduction, polyp stage for asexual reproduction and feeding.

• Medusas produce sperm or eggs; after fertilization, the egg becomes an embryo. The embryo develops into a polyp attached to a substrate.

  • A polyp can be feeding polyp or reproductive polyp. Reproductive polyps produce Medusa.

  • Feeding polyps capture water; reproductive polyps produce Medusa.

  • Feeding polyps share nutrients with reproductive polyps.

• *Examples:

  • Hydra.

  • Portuguese man o' war: It is not a single animal but a colony. It includes a gas bladder and tentacles (can be as long as a hundred feet). Each cell function differently.

Scyphozoa

• Often referred to as jellies; the medusa stage is dominant.

• Jellies belonging to the Scyphozoa class do not have a vellum.

Cubozoa

• Known as box jellies; their jelly/medusa shape is box-like.

• They also have four tentacles found in the corner.

• Cubozoa has a vellum.

• Cubozoa possesses good eyesight, with the ability to differentiate shapes of light.

• They move toward darker shapes of fish or some kind of animal to prey on.
  *Example: Sea wasp. A single sea wasp has venom to kill up to sixty people within three minutes. Vinegar does help, but it will not help with seawas venom.

• Alcohol must not be put on a person's body who is stung because it will help Ashley distribute and cause the poison to be absorbed.

Anthozoa

• Include corals and sea anemones; believed to be the most evolved.

• Bodies have distinctive areas.

• Actinopharynx represents a primitive digestive system.

• Mesenteries: the folding inside the digestive tract; improve surface area to volume ration and more efficient food breakdown as well as food absorption.

• Anthozoa includes c pens and c fans.

• Some possess a mutualistic relationship with algae called zooxanthellae algae.

  • Algae are photosynthetic, producing sugar and sharing it with anemones, where sea anemones provide a home for the algae.

• Some sea anemones have relationships with sea anemones.

  • Clownfish covers its body with mucus to disarm the sea anemone.

• Corals produce skeletons made of calcium carbonate.

  • They use their tentacles to capture prey.

  • Some also have Zoon Valley algae.

• Coral bleaching: the situation when Expel algae out of its body; it may happen due to climate changes, warmer ocean temperature etcetera

• Corals prevent beaches from currents and strong waves. Cancer drugs have been discovered based on research on corals.
  *Great Barrier Reef in Australia stretches over a thousand miles.
  40 to 50% of coral have been dead.

Flatworms (Platyhelminthes)

• Include planaria, tapeworms, and flukes.

• Flat, bilaterally symmetrical, unsegmented bodies.

• Acoelomate, hermaphroditic (some are free living, some are parasitic)

• Triploblastic.

• Incomplete digestive tract.

• Possess simple organs and cephalization (a head region).

• Breathe directly through their skin in wet environments.

• Reproduce sexually and asexually (mostly sexually)

  • Marine flatworms reproduce sexually via penis fencing (hypodermic insemination).

  • Fighting to poke each other instead of being poked because pregnancy causes to spend more energy and time to feed potential, you know, offspring.

  • Asexually reproduce through transverse fission and strabulation.

Classes of Flatworms

Tribularia, Monogenea, Trematoda, Cestoda

Tribularia

• Mostly free-living, freshwater (planaria), some marine.

• Planarians can regenerate even when cut into 30 pieces.

• Possess eyespots to detect light.

• Primitive brain called ganglia.

Monogenea

• Small ectoparasites of fish (gills, fins, rectal cavity).

• Reason to worry the sushi.

• They have a single host.

• If fish is caught and does not put in a coal, worm will burrow into the tissue and flesh of that fish, can can that eat it.

Trematoda

• Flukes: Are parasites of vertebrates; main affect fish and humans.

• Flukes have two hosts.

• Intermediate host: Parasite lives in and becomes sexually matured in, but they do not reproduce.

• Definitive host: Parasite will use this to made with one another and produce eggs.
  *Example of flukes is schistosoma. Causes schistosomiasis. Humans shed eggs. Larvae then go into and find Snails.
  The human is the is the is the definitive host. And the snails are the intermitted host.
  Humans is also the definitive host of malaria as well.

Cestoda

• Tapeworms: All endoparasites of vertebrates, including humans.

• Can be very long (100+ feet in whales, 60 feet in humans).

• Lacks a mouth or digestive system; absorbs nutrients and oxygen through their skin.

• Hermaphrodites, but typically don't self-fertilize.

• Anatomy:

  • Scolex (head): Hooks/spikes to attach to the intestine.

  • Proglottids: Segments.

  • Gravid Proglottids: Segments farthest from the head, containing mature eggs/sperm; shed in feces.

• The tapeworm diet, is based on the fact that people infect themselves. in the US does not worth because we eat a lot, therefore, doesn't make us lose weight.

• To not get infected, simply cook your food thoroughly.