Test 4/Final Flashcards
the round worms
Phylum Nematoda
They are typically considered the most abundant and widespread animals on the planet. They are found from the bottom of the deepest ocean to near the tops of the highest mountains, from the tropics to polar regions, and from every conceivable habitat.
Nematodes
These are also found in or on most other types of organisms as parasites or commensals: everything from earthworms, insects, molluscs, fish, reptiles, birds, and mammals, including humans.
Nematodes
How can Nematodes be harmful to the economy?
loss of agricultural production, pasture and turf damage, invasion of forest trees, adverse effects on the health of wild and domestic animals and humans
How are Nematodes beneficial to the economy?
controlling soil nutrient cycling, controlling harmful species, serving as animal models (C. elegans) for studying aging and development
How are the Nematodes so successful?
Simplicity (a simple design that works great in very common environments)
The nematodes are a very __________ group in terms of their structure (both external & internal).
homogeneous
The following characteristics belong to which phylum usually small (most species 1-2 mm long), cylindrical body, tapered at both ends, no segmentation or appendages, complete digestive tract, eutely
Nematode
What does the term eutely mean?
constant cell number, growth by increasing cell size, not number
Their lack of any indication of true segmentation separates and distinguishes them, as well, from the annelid worms, such as “bristle” and earth worms.
Phylum Nematoda
This is a complex and multilayered structure that is secreted by an underlying epidermis.
The Nematode’s cuticle
What does the cuticle’s major layers consist of?
How many layers of this are there? How are they arranged and why?
protein collagen, at least 3, like plywood (layers alternate in direction). This gives strength and resiliency to the body wall.
Nematodes: The place where these creatures mature and reproduce in the human body.
the small intestine
Nematodes (Hookworms: Nectator americanus): The place where these creatures enter the human body.
The feet
Nematodes: These tough fibers are laid down in layers and make up the cuticle.
Collagen
Nematodes: Since they molt their cuticles, this phylum is grouped with others that can do the same – the __________.
Ecdysozoa
Nematodes: This phylum’s key to success seems to be their _________.
Simplicity
Echinoderms: Shared derived characters: radial, indeterminate cleavage, blastopore becomes anus, mouth forms from second opening
Deuterostome
Echinoderms: central disc with five or more arms, use tube feet for locomotion
subclass Asteroidea
Echinoderms: Pincer-like structures on sea stars. Some keep debris off body, others used for defense or capturing prey.
Pedicellaria
Echinoderms: If you irritate or attack me, I’ll aim my backside at you and shoot sticky red tubules out of my anus. That will teach you a lesson!
Sea Cucumber (Class Holothuroidea)
Hemichordates: part shaped like an acorn, muscular & covered with mucus, used for burrowing & moving within burrows
proboscis
Hemichordates: The class name literally means “gut breather.”
class Enteropneusta
Hemichordates: Class _____________ - form colonies, proboscis is shield shaped, most live in deep water, trunk is short & sac-like, digestive tract is U-shaped
class pterobranchia