24.5 Diversity of Life: Animalia key p. 193
- What characteristics do protostomes and deuterostomes show? Which phyla are protostomes and which phyla are deuterostomes?
develop mouth from the blastopore, spiral cleavage, split mesoderm to develop coelom.
Lophotrochozoa: Platyhelminthes, Rotifera, Mollusca, Annelida.
Ecdysozoa: Nematoda, Arthropoda.
develop anus from the blastopore, radial cleavage, infolding of archenteron to develop coelom.
- Contrast Acoelomate, Pseudocoelomate, Eucoelomate body plans. List the phyla that show each of the body plans. What are the advantages of having a coelom?
no body cavity - Platyhelminthes.
body cavity not completely lined by mesoderm - Nematoda.
body cavity completely lined by mesoderm tissue - Mollusca,
A coelom provides cushion, room for organs.
- What is the function of the spicule? What are choanocytes?
Spicule provides support, protection.
Choanocytes use flagella to move water, engulf food by phagocytosis.
- What is the most commonly seen life stage of the Hydrozoa?
Polyp (Obelia and Portuguese man-of-war also have medusa stage)
- What is the most commonly seen life stage of the Scyphozoa?
- What is the only life stage shown be members of the Anthozoa?
Phylum Platyhelminthes p. 194
- What are the environmental forces that could have selected for bilateral symmetry?
Bilateral symmetry allows complex movements such as crawling, burrowing, flying, or swimming. Cephalization for sensing.
- What are the functions of the ocellus, intestine, and pharynx?
Ocelli (eyespots) detect light;
intestine (gastrovascular cavity) digests food;
pharynx ingests food and is also used for excretion.
- What is the function of the opisthaptor?
Opisthaptor in Monogenea is located at posterior and used to attach to fish host.
- What is the importance of the cercaria?
Cercaria are the motile larvae of Trematoda that escape from intermediate host to penetrate primary host.
- Provide the functions of the scolex and proglotids?
The scolex of Cestoidea attach to host intestines;
proglotids produce eggs.
- What life stage causes the Hydatid cyst?
Hydatid cyst is juvenile stage of flatworms.
- What structural complexities do the Nematoda show which are not shown by the Platyhelminthes?
- Identify the disease caused by Trichinella, the means of contamination, and the symptoms of the disease.
Trichinosis is caused by eating undercooked pork;
symptoms include nausea, diarrhea; then joint/muscle pain, coordination problems.
- Which phylum is the Rotifera related to? Explain why.
Mollusca; both have lophophore and belong in Lophotrochozoa.
- What are the characteristics of the Mollusca? What structural complexities do the Mollusca show which are not shown by the Nematoda?
Muscular foot, visceral mass, mantle;
Mollusca possess true coelom.
Phylum Annelida p. 195
- What structural complexities are shown by the Annelida which are not shown by the Nematoda?
- Compare the number of antennae, legs, and major body parts among the spider, crayfish, centipede, and insect.
| ||Antennae||Legs||Body parts|
|Crayfish||2 pairs||10||cephalothorax, abdomen|
|Centipede||1 pair||1 pair legs/segment||head, trunk (thorax/abdomen)|
|Insect||1 pair||6||head, thorax, abdomen|
- Count the pairs of legs on the millipede and centipede. Why so many legs?
Millipede: 2 pairs legs/segment, centipede 1 pair legs/segment.
Many legs provide flexibility in crawling and redundancy.
Phylum Echinodermata p. 196
- Why the seemingly regression to a radial (more of a pentaradial) existence? What are the selective advantages to being pentaradial?
Pentaradial symmetry allows ability to crawl on rocks, open shellfish.
- What are the characteristics of the Craniata?
Craniata are chordates that have a head.
- What distinguishes the Myxini from the Cephalaspidomorphi?
Cephalaspidomorphi (lamprey)) are jawless fish that possess vertebrae; Myxini (hagfish) do not have vertebrae.
- Contrast the differences and similarities among reptiles, birds, and mammals with respect to type of metabolism
and number of chambers in the heart. Why the need for extra chambers to the heart (relate to metabolic rate)?
Extra chambers allow segregation of oxygenated and oxygen-poor blood, increasing oxygen-carrying capacity of blood.