The ________________________________ contains some _________________ and includes a number of parasitic organisms.
The first group of parasitic animals we will examine are the HELMINTHS – ________________________________
Helminth Phyla Phylum _____________________________ - Phylum _____________________________ - Phylum _____________________________ - (of little economic importance – we will not study them) ______________________________ - study of parasitic worms.
Phylum Platyhelminthes – Chapter 13 The flatworms are the planarians, trematodes, and tapeworms. Forms present in the phylum? ____________________________________________ ____________________________________________ ____________________________________________
Phylum Platyhelminthes – Chapter 13 Characteristics of the Phylum Platyhelminthes: 1. 2. 3. 4.
Characteristics of the Phylum Platyhelminthes cont.
first animal group to have this system
Characteristics of the Phylum Platyhelminthes cont. 7. ________________________________________ ________________________________________ - absent in the tapeworms 8. _______________________________________ _______________________________________ - limits size so most flatworms are small and soft-bodied. 9. ________________________________________ - most flatworms are _________________ - both male and female organs occur in an individual
Taxonomy of the Phylum Platyhelminthes We will use the traditional taxonomy: Phylum Platyhelminthes Class Turbellaria – planarians Class Monogenea – monogenetic flukes Class Trematoda – digenetic flukes Class Cestoidea – tapeworms As in the Protozoa, a new taxonomic scheme has been proposed which divides the Turbellaria into several taxa. However, we will not use the new scheme and use the traditional taxonomy.
Most turbellarians are free-living scavengers, but some are ___________________________ on other invertebrates.
2 members of Class Monogenea Polystomoidella – parasite in the urinary bladder of the snapping turtle Microcotyle – parasite on the gills of the sheepshead fish. Note numerous clamplike structure on the opisthaptor.
Class Trematoda Trematodes are __________________________________ in all classes of vertebrates. These worms have become structurally adapted for a parasitic existance: 1. possess ___________________for attachment to host 2. have many types of ____________________to produce secretions for ___________________________________ or to produce a ___________________________ 3. have high _________________________(reproductive capacity) to increase chances of completing complex life cycles
Subclasses of the Class Trematoda Of the 3 subclasses in the Class Trematoda, we will examine 2 of them: Subclass Aspidobothrea (= Aspidogastrea) Subclass Digenea
Subclass Aspidobothrea Most are parasites in the viscera of ____________________ A few are parasitic in the intestines of ________________________________________________ Cotylogaster - a parasite in the small intestine of the sheepshead fish- is a representative of this subclass.
Subclass Aspidobothrea - Cotylogaster Characteristic structure is ______________________ composed of numerous shallow depressions called ____________________ (this sucker resembles bottom of tennis shoe)
Subclass Aspidobothrea - Cotylogaster Adults are monoecious: Male and female reproductive organs are similar to those of digenetic trematodes (I will discuss these shortly) Importance?
Life cycle of Cotylogaster Life Cycle – Addition of fish host: Adult in fish intestine clam eaten by fish Adult in clam viscera egg released into water hatches enters clam via free-swimming _______________________ incurrent siphon - has tufts of cilia - eyespots - long unbranched intestine
Most abundant subclass - contains the digenetic trematodes
All are _________________________ in all classes of vertebrates
inhabit many vertebrate organs (not limited to the intestine)
many species infect humans and domestic animals and are of medical and veterinary importance
Life cycles are complex involving at least 2 hosts - term "digenea" means 2 beginnings representing the 2 hosts
first intermediate host is a ______________________________
definitive host is a ________________________________
many life cycles have a third host between the snail and vertebrate - the second intermediate host - this is an __________________________ ___________________________________________________________
Ma ny larval stages occur in the intermediate host(s) - _____________________________________ occurs in some of the larval stages
Adults occur in the definitive host - ___________________________________ occurs in this host
Morphology of an Adult Digenetic Trematode
Characteristic structures are the 2 suckers
_____________________________ - at anterior end surrounding mouth - for attachment and feeding
_____________________________ (= ventral sucker) - located midventral to oral sucker - no internal opening - for attachment to host
Suckers are strongly muscularized consisting of bands of smooth muscle
Trematode Digestive Tract ___________________________ is contained in oral sucker Muscular ___________________ creates sucking action Short esophagus leads into 2 long blind-ending _________________ (= intestinal ceca) No anus so ______________________________________________________
Digestion and the Parenchyma Food taken into the digestive tract consists of ______________________________ ______________________________ Proteins are digested in the lumen of the intestine and _______________________________are absorbed through the intestinal epithelium.
Parenchyma PARENCHYMA - loosely arranged cells filling space between internal organs. Major function is:
Trematode Excretory System
EXCRETORY SYSTEM removes excess water that has diffused into worm
_______________________________ _______________________________ occur throughout the body
cells contain beating flagella that create a hydrostatic pressure which draws water from the parenchyma into the collecting duct
flame cells are seen only _______________________________
- at the posterior end of the worm:
Trematode Nervous System Ladder-type system consisting of anterior ganglionic mass, lateral nerve trunks, and connecting commissures. Sense organs of adults are at the cellular level within the tegument - ______________________________________________________________ Sense organs of free-swimming larval stages (miracidium & cercaria) are well developed: ______________________________________________________________
Trematode Reproductive Systems Reproductive systems are extremely elaborate and specialized Digenetic trematodes have ___________________________ - some produce as many as 25,000 eggs per day. Most digenetic trematodes are _________________________ - schistosomes are only dioecious group - monoecious forms commonly cross-fertilize but self-fertilization is possible
Male reproductive system Two testes – function?
Male reproductive system Trematode sperm are unusual for 2 reasons: 1. ________________________________________________________ 2. ________________________________________________________ nucleus 2 flagella mitochondrion
Male reproductive system Shape and position of the 2 testes are important taxonomic characters Shape: Position: Combination of shape/position: branched tandem testes; lobed opposite testes, etc.
Male reproductive system Sperm ducts consist of 2 ____________________________ which join to form a single _______________________ Vas deferens leads into the cirrus sac (= cirrus pouch) that contains: - ____________________________ - sperm-storage area - _____________________________- produces fluids to maintain sperm - _____________________________- male copulatory organ which can be everted through the ______________________________ for copulation
Female reproductive system Single ovary produces ___________________________ which pass along the oviduct to the ___________________________ Taxonomic importance?
Female reproductive system Shape and position of the ovary in relationship to testes important in identification Shape: oval lobed branched
Female reproductive system Ootype is region of female system where: (1) ____________________________ (2) ____________________________
Female reproductive system
Structures associated with the ootype:
1. ________________________ - sperm storage area of the female system
2. _________________________ is a short duct which leads from the seminal receptacle to the outside.
Laurer's canal was once a vagina but has lost this function and now serves to ________________________________________________
Female reproductive system Vitellaria (= vitelline glands) - occur in _____________________ which generally stain intensely - secrete ______________________ which will coalesce in the ootype to form the _______________________ - vitelline cells containing this protein pass along vitelline ducts which join and lead into the ootype
Female reproductive system Mehlis' gland - surrounds the ootype - produces secretions that ______________________________ ______________________________in the ootype - stains a light pink
Female reproductive system ___________________________ leaves from the ootype and consists of a long, often highly coiled duct containing eggs and sperm As the eggs pass through the uterus, 2 processes occur: 1. 2. Uterus function -
Female reproductive system Anteriorly, the uterus leads into a strongly muscularized duct called the __________________________ - this functions as an ovijector, forcing eggs out the common genital pore - metraterm joins the cirrus sac at the __________________________
Trematode Anatomy – Representives We will examine the anatomy of Prosthogonimus macrorchis, the chicken and duck oviduct fluke, in lab.
Trematode Anatomy – Representatives We will examine the anatomy of Quinqueserialis , the muskrat cecal fluke, in lab.
Trematode Anatomy – Representatives We will also examine the anatomy of the immature adult of Leucochloridiomorpha from a snail. We’ll examine living specimens to see excretory system and beating of the protonephridia. We will compare living specimen to stained whole mount.