Biology Lab #23
Terms in this set (46)
Food consists of organic molecules made by other organisms.
Animals with a backbone
Animals without a backbone
[Invertebrates] Lacking a true body cavity. Body cavity lined with mesoderm.
Advantages of a coelem
1. Digestive system and wall can move independently
2. Internal organs can become more complex
3. Coelemic fluid can assist respiration, circulation, and excretion
4. For some animals, coelem serves as hydrostatic skeleton because muscles can work against a fluid-filled cavity.
Animals has no particular symmetry.
Animal is organised circularly and, just as a wheel, two identical halves are obtained no matter how the animal is longitudinally sliced.
Which of the phyla in the tree are the Radiata?
Comb jellies and Cnidarians
Adult animal has definite left and right half.
- All other structures are derived from them.
- One main event during the development of animals.
Outer germ layer of an animal.
- A tissue layer that becomes the skin and nervous system.
Inner germ layer of an animal.
- A tissue layer that becomes the gut.
Middle germ layer of an animal.
- A tissue layer that becomes the muscles of an animal.
Which phyla only has two layers?
Comb jellies and Cnidarians
Pattern of development in which the first opening of the embryo is the mouth.
Pattern of development in which the first opening is the anus and the second opening of the embryo is the mouth.
Lab #23 Introduction to Invertebrates
Which pattern of development do the flatworms, rotifers, and roundworms have?
Protostome pattern of development.
Sponges (Phylum Porifera)
Live in water, mostly marine, attach to rocks, shells, and other solid objects.
- Single sponge can become a colony by asexual budding or fragmentation.
- Reproduce sexually by producing eggs and sperm.
- Sessile filter feeders
Anatomy of Sponges
No well-defined tissues; assymetrical or radially symmetrical and sessile (immotile)
Sponges have few types of cells:
Flagellated collar cells (choancytes). They take in suspended food particles from the water and digest them for the benefit of all other cells.
- Movement of flagella keep water moving through the pores of the central cavity and out the osculum of a sponge.
Main excurrent opening.
Fine projections over the body and especially encircling the osculum
Cnidarians (Phylum Cnidaria)
Tubular or bell shaped animals that live in shallow coastal waters, except for the oceanic jellyfishes.
- Two basic body forms are seen among cnidarians:
Polyp ---> Mouth is directed upward
Medusa ---> Mouth is directed downward
Polyps take care of their own needs for the two life functions of a respiratory or circulatory system since planarians and cnidarians have no respiratory or circulatory systems.
Specialized stinging cells.
- Each cnidocyte has a fluid-filled capsule called a nematocyst which contains a long, spirally coiled hollow thread.
Diversity of Cnidarians
How can radially symmetry benefit an animal?
They can move in any direction and if a body part is lost, others can compensate and it will grow back.
Anatomy of Hydra
Hydras exist only as sessile polyps; there is no alternate stage.
- tentacles that surround mouth, large gastrovascular cavity, and basal disk
- Gastrovascular cavity has a single opening that is used both as an entrance for food and an exit for wastes.
Flatworms (Phylum Platyhelminthes)
Bilaterally symmetrical animals that can be either free-living or parasitic
- Free-living flatworms = planarians (more complex than cnidarians)
- Ectoderm, endoderm, and mesoderm present
- Pharynx extended through the mouth
Posses both male and female sex organs.
- Flatworms are hermaphroditic
Why is it advantagous for an animal to be hermaphroditic?
If a flatworm/animal is solitary, it can reproduce by itself. Can be genetically diverse by sexual reproduction.
- Planarians practice cross-fertilization.
Three-part gastrovasucular cavity
- The excretory organs are called flame cells collect fluids from inside the body and send via a tube to an excretory pore
- The nervous system contains a brain and lateral nerve cords connected by transverse nerves = ladder-like.
What is the advantage of a gastrovascular cavity that ramifies throughout the body?
Higher surface area for the distribution/absorption of nutrients.
Tapeworms (also known as cestodes)
Consist of a head = scolex with suckers and hooks and proglottids = segments of the body
Flukes (also known as trematodes)
- Parasites that inhabit blood, liver, or lungs.
- Come from under-cooked fish or shellfish
Male and female organs are in separate individuals.
- Human blood flukes are dioecious.
Why would endoparasites such as flukes and tapeworms have a dispersal problem?
They aren't as exposed since they reside in an internal environment; Can be attacked by immune system.
Table 23.2 Planarians Versus Parasitic Flatworms
Look in lab book
Roundworms (Phylum Nematoda)
Like planarians, roundworms have three germ layers, bilateral symmetry, and various organs - including a well developed nervous system.
- Planarians and roundworms are nonsegmented; no repeating units.
- Parasitize both plants and animals (cause diseases)
- Pinworms and hookworms = roundworms
- Cause elephantiasis
- Ex. Ascaris and Trichinella (causes Trichinosis)
- Just like arthropods, roundworms molt
Complete digestive tract
- Roundworms have both a mouth and an anus
- Roundworms have a pseudocoelem
A body cavity that allows space for the organs is completely lined with mesoderm.
How would the presence of a complete digestive tract and a pseudocoelem lead to complexity?
All organs work together to complete a specific function or functions.
Caused by a roundworm called a filarial roundworm
- Infects lymphatic vessels and blocks the flow of lymph
- Limbs will become massively swollen
Rotifers (Phylum Rotifera)
Freshwater animals that are important constituents of the plankton of lakes, ponds, and streams, and are a food source for fish and other animals.
- Like roundworms, have a pseudocoelem and complete digestive tract with a mouth and anus.
- Cilia around the mouth like a wheel.
- Rotifer = "wheel bearer"
- Have eyespots and flame cells
- Trophi = jaws
Serves for both feeding and movement