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
Hemichordates: Recent DNA evidence suggests that this phylum is more closely Related to (Echinodermata or Chordata).
Echinodermata
Chordates: 90% of the invertebrate species within this phylum are members of the __________ subphylum.
Urochordata
Chordates: flexible, supporting notochord; dorsal, tubular nerve cord; pharyngeal slits; muscular postanal tail; endostyle or thyroid gland
the defining characteristics of Chordates
Chordates: Members of the Urochordata produce a protective covering of protein and a polysaccharide similar to cellulose.
tunic
Chordates: Say hello to our closest non-vertebrate kin!
the Cephalochordata, lancelet, or amphioxus
Chordates: Class ________ - found in most areas of the oceans, retain their larval form as adults, make big gelatinous “houses” which act as giant filters for feeding, frequently abandon their dirty house & make a new one; abandoned houses, sinkers, are food for many ocean animals
Class Larvacea
The Nematode’s cuticle is permeable to water and gases. Therefore, gas exchange occurs how?
across body surface
Nematodes do not have ____ muscles, only _____ muscles. Therefore, how do they move?
circular, longitudinal, by alternating the muscles on their dorsal then ventral surfaces; this creates a whip-like up & down movement
What is important for a Nematode’s locomotion?
their hydrostatic skeleton & cuticle
Why do Nematodes have high internal pressure (more than human blood pressure)?
1) non-stretchable cuticle 2) muscles are always partially contracted, squeezing the internal fluids, and 3) osmosis causes water to move into their bodies from the outside {which is why they are so round}
Nematodes: Contraction of a ____ on one side is transmitted through the ____ and stretches the ___ on the opposite side of the body. When the muscle relaxes, the cuticle contracts and the body returns to its ______.
longitudinal muscle, hydrostatic skeleton, cuticle, resting position
Nematodes reproduce ____ and most are (mon/di)oecious. Fertilization is ____, sperm are _____, and there is _____ larval stage.
sexually, dioecious.
internal, amoeboid, no distinct
Male/Female Nematodes: have a cloaca, a common opening for the anus and genital pore. This opening is located slightly in front of the worm’s posterior end. It generally has a pair of copulatory spicules which protrude from the cloaca.
Male
What are male nematode’s copulatory spicules for?
To assist in holding the mate’s genital aperture open during copulation.
The (male/female) genital aperture is located about midway along the animal, on its ventral surface.
Female
These characteristics describe what? most are carnivores. However, some feed on algae and fungi and some are detritivores. Others feed on plants, especially the roots. many root feeding ones are major agricultural pests estimated to destroy 12% of the world’s cash crops annually
Free-living nematodes
The following are all _____. Ascariasis: Ascaris lumbrioides, Pinworms: Enterobius vermicularis, Whipworms: Trichuris trichiura, Hookworms: Necator/Ancylostoma, Trichinosis: Trichinella spiralis, River blindness: Onchocerca volvulus, Guinea worm: Dracunculus medinensis, Canine Heartworm: Dirofilaria immitis, Filarial worms: Wucheria/Loa/Brugia
human-parasitic nematodes
These worms ingest blood. <100 worms don’t cause much trouble & may not be noticed. >500 worms make the host anemic & weak from blood loss. These host will suffer severe abdominal pain, fever and dizziness.
Hookworm (Necator americanus
For a long time nematodes were grouped with animals that have a ____. However, it turns out that a lot of nematodes are ____. Therefore, the various groups were all split out and each made into their own phylum when it was decided that they were not a ____ group.
pseudocoelom. acoelomates. monophyletic
What kind of symmetry do the echinoderms have?
radial
Since the echinoderms are radially symmetric, why are they placed in the Bilateria, instead of the Radiata?
because their radial symmetry was secondarily evolved from bilateral ancestors (the bilateral body plan is still seen in the echinoderm larvae)
Their radial symmetry is imposed on a relatively advanced coelomate body plan which includes a endoskeleton formed from mesoderm. This partly explains their success as a group. Who are they?
Echinoderms
This phylum is unique in that they have combined mobility with radial symmetry & show lots of different lifestyles and feeding methods. They are similar to other radial animal in that they have a non-centralized nervous system (no brain). This lets them deal with their environment equally from all sides.
Echinoderms
Echinoderms are _____. They have shared derived characters including radial, have indeterminate cleavage, the blastopore becomes the anus, and the mouth forms from the second opening.
deuterostomes
Marine animals with
spiny “skin”: endoskeleton of calcium carbonate, well-developed coelom, water vascular system, tube feet, mutable connective tissue, and Larvae exhibit bilateral symmetry but, most adults exhibit pentaradial symmetry
Phylum Echinodermata
Many echinoderms have certain connective tissues that contribute to their body “tone” through rapid changes in their properties. In a matter of seconds or minutes the fibers of these tissues can become relatively rigid, thereby reducing body flexibility. What are these tissues called?
mutable connective tissue
Mutable connective tissue is not ______. It is involved in __, ___, and the intentional shedding of arms or ____ when the animals are attacked
muscles; locomotion, feeding; viscera
Sea lilies and feather stars are part of which class of Echinoderms?
Class Crinoidea
Bristle stars are part of which class and subclass of Echinoderms?
Class Stelleroidea, Subclass Ophiuroidea
Subclass Asteroidea of Phylum Echinodermata consist of what?
sea stars
Class Echinoidea of Phylum Echinodermata consist of what?
sea urchins, heart urchins, & sand dollars
Class Holothuridea of Phylum Echinodermata consist of what?
sea cucumbers
Except for a few brackish-water species, echinoderms are strictly ____.
marine
Why have Echinoderms been unable to invade land or freshwater?
Probably because of their method of exchanging gases across their skin and because they don’t have any excretory or osmoregulatory structures.
Almost all _____ are benthic and in some parts of the deep sea they may compose 95% of the biomass.
Echinoderms
What phylum? spiny skin, lack cephalization, no anterior or posterior end so, refer to aboral and oral surfaces
Echinoderm