Grazers and browsers Flashcards
How do grazers/browsers feed?
Mobile consumers of sessile prey (usually plants, fungi, algae), cropping exposed tissue without killing the prey.
What are common structures possessed by grazers/browsers to aid in feeding?
Hard, biting mouthparts (radulae in gastropods, aristotle’s lantern in sea urchins, sclerotized jaws in insects)
What are some challenges of being a grazer/browser?
Chemical defences evolved by prey species, as well as the small proportion of digestible material.
How do grazers/browsers overcome challenges?
Indigestible materials - enzymes, evolution of very long mid gut regions, aid of symbiotic bacteria. Also a large crop helps.
How is the american cockroach segmented?
Head, thorax, abdomen. 2 pairs of wings. 6 pairs of strong, spiny legs.
Head of cockroach
Flattened dorsoventrally, mouthparts extend posteriorly from narrow end. Head usually faces substratum.
Cockroach head when feeding
Face held vertically with the mouthparts located ventrally toward substratum
Cockroach mouthparts
Labrum and labium
Labrum of cockroach
Upper lip, sensory in function and helps press food against the mandibles.
Labium of cockroach
Lower lip, sensory in function and helps press food against the mandibles, have sensory palps.
How do cockroaches eat?
First stage: tearing and chewing by sclerotized edges of the mandibles and maxillae.
What are important features of the cockroach digestive system?
White fat body, tracheae, crop, digestive ceca, and malphigian tubules.
What is the function of a cockroach fat body?
storage of lipids, glycogen, protein reserves. stored food supports survival over long periods of starvation.
varies in size depending on extent of starvation.
Cockroach site for intermediary metabolism, amino acid synthesis, blood glucose regulation, vitamin synthesis, and uric acid storage.
Fat body
Where are the Cockroach tracheae located?
One pair from thorax to head, one pair beside the heart.
What is the function of the cockroach foregut?
Mechanical digestion, trituration, chemical digestion, storage
What is the function of the cockroach midgut?
Enzyme secretion, chemical digestion, absorption
What is the function of the cockroach hindgut?
Water reclamation, feces formation, storage. Also a storage kidney that secretes uric acid.
What are the components of the cockroach foregut?
Mouth, pharynx, esophagus, crop, proventriculus. Have white salivary glands in the esophagus.
What are the components of the cockroach midgut?
Midgut and digestive ceca
What are the components of the cockroach hindgut?
Ileum, colon, rectum (ileum and colon combine to form intestine)
What occurs in the cockroach crop?
May contain large air bubble. Hydrolysis occurs here, making use of enzymes from the salivary glands (amylase) and the digestive ceca
What is the function of the cockroach proventriculus?
It is the gizzard. Has walls with teeth to chew food after the mandibles and maxillae have already started mechanical digestion.
What is the function of the cockroach digestive ceca?
Beginning of midgut, it is 8 long fingerlike diverticula. Increase SA for absorption for secretion of enzymes
These enzymes: invertase, lipase, maltase, protease, and lactase are produced where in the cockroach?
Digestive ceca and midgut.
Long, slender, white, threadlike, blind-ending tubules in the cockrach, in 6 clusters
Malphigian tubules
What is the function of the malphigian tubules?
Excretory and osmoregulatory.
What does the cockroach rectum have that helps remove water from the forming feces?
The wall of the rectum has 6 rectal pads, reclaiming water when it is scarce.
What do sea urchins eat?
Seaweed tissue and bacteria living in their gut.
How do sea urchins eat?
Cilia create a water current to carry the food, also tube feet pass the food to the urchin’s mouth.
What is the function of aristotle’s lantern?
Dental apparatus used to scrape algae and food from rocks.
What kind of snail did we look at in lab?
Helix; garden snail.
What makes the snail special?
It is a pulmonate gastropod with a vascular lung and NO GILL. The only successful terrestrial gastropods.
What does the shell of the snail look like?
Coiled and torted. Covered by a thin layer called the periostracum.
What is the snail aperture?
Large opening where the living animal portrudes
What is the difference between dextral vs sinistral?
Snail shell aperture on the right = dextral, left = sinistral.
What is a snail whorl?
Each coil of the shell = a whorl. Nuclear whorl = oldest part of shell, smallest whorl.
What is the snail’s visceral mass?
Sits on dorsal surface of foot and coils up into spiral shell, asymmetrical.
What is the function of the snail foot?
Large muscular organ
How does air enter the snail’s “lung”?
Pneumostome, small opening
How does blood travel in the snail?
From blood spaces and returns to the heart via vessels on the dorsal surface of the mantle cavity. Eventually lead to the heart.
Snail Aorta
Large vessel from ventricle into the body.
What does the snail buccal mass look like?
It is in the head, it is a large ovoid mass of muscle containing the pharynx and radula.
What does the snail crop look like?
Dark, tubular, lies on the left, extends the length of the hemocoel.
What does a snail use to eat?
Their radula.
What is the function of a snail’s albumen gland?
Reproductive, secretes nutritive material around the fertilized egg.
How do snails reproduce?
Hermaphroditic with internal fertilization. One snail drives a “love-dart” into the other’s body with muscular contractions of the dart sac. Dart sac penetrates the epidermis of the partner.
What do the mucous glands look like in the snail and what are they used for?
Filamentous components. Secrete mucous for lubrication.
