Arthropods Flashcards
What is the most succesfful and diverse group of animals?
Arthropods
85% of all species
Most dominate in fossil record
Where can arthropods live
Cosmopolitan (air, land and water)
The body of arthropods is ______ and possess _______
Segmented
Jointed appendages for feeding and movement
Phylum Arthropoda unique characteristics
- Body epidermis is composed of chitonous exoskeleton which is jointed, segmented and hardened/sclerotized
- lack locomotory cilia in larval and adults stages
Important Arthropod groups include:
- Insecta: anta, dragonflies and bees
- crustaceans: crabs, lobsters and shrimp
- arachnids: spiders and scorpians
- myriapods: centipedes and milipedes
Tagmatization
Body divided into segments with specialized functions
Ex: insecta and crustaceans have 3 distinct body segments (head, thorac and abdomen)
Arthropods possess __________ made up of ______ which is shed periodically
Jointed, flexible exoskeleton
Chiton
Reason for success of the members of the phylum
Exoskeleton is secreted by what:
Epidermal cells
In terms of body plan and development, arthropods are ________ and ______
Bilaterally symmetrical and triploblastic
Body organization of arthropods is of an _____ level
Organ-system
4 layers of exoskeleton
- Epicuticle (outer layer)
- Endocuticle (differ among species)
- Epidermis
- Basment membrane
Exoskeleton is similar to shells of molluscs but differ in
Function and composition
In addition to protection, exoskeletong plays a role in
Movement and composition
Sclerotization/ tanning
Hardening of the cuticle by cross-linking of proteins of the epicuticle
Epicuticle
- Waxy, made up of layers of lipoproteins, underlaid by layers of lipids
- water impermeable (resistent to water loss by dehydration)
- disadvantage: can’t function in respiration directly
- thin, composed of 3% of wrthropod exoskeleon
Procuticle
Forms bulk of arthropod exoskeleton
- exocuticle
- endocuticle
Made largely of chitin (polysaccaride) and proteins
Biotechnological application of chiton
-Chiton has unique characteristics of strength, non-allergenic and biodegradable thus, it is applied as follows:
- dissolved and reformed into fibers for fabrics abd surgical sutures
- making capsulated therapeutic drugs
- proposed for yse as plastic wrap for processed foods: alrhough not digestible by vertebrates
- as food additive: reduce calorie and cholesterol uptake
- purifying agent: high binding potential was harnessed for removing organic and inorganic wastes from table water and sewage purification
The major body cavitt of an arthropod is a
Hemocoel forming the circulatory system
The true coelom of arthorpods is
Greatly reduced to the spaces of the genital and excretory organs as it is encased in a rigid exoskeleton
Arthropods have a complete _____ system
Digestive
With mouth and anus
Excretory organs of arthropods
Green glands, malpighan tubules, cocal glands
Nervous system of arthropods
Similar to annelids with a dorsal brain connected with a nerve ring to double ventral nerve cord
Sensroy organs of arthropods
Eyes (simple or compound), chemo-and tactile receptors, balancing and auditory organs
Molting
- process of shedding of exoskeleton and or cuticle lining the inner gut. Also called Ecdysis
- ensures growth and decelopment among arthropods
- involves secretion of new cuticle underneath the old one by underlying epidermal cells, followed by partial enzymatic degrading of old cuticle which is released.
- newly secreted soft cuticle ensures growth of the arthropod prior to hardening
In crustaceans, secretion of new cuticle requires _____
Cryptocyanin (substance evolved from hemocyanin, copper based protein which function in oxygen transport
Motling is regulated by neural and hormonal controls known as
Ecsysteriod hormine
Motling is induced by release of _____ in head of crustacean or by induction of ________ in the thorax of insects
Y-organ
Prothorax gland
Morling in crustaceans is inhibited by _____ until next molting period is reached
X-organ
Nervous and muscle control in arthropods
Nervous control is theough complex network of axons (slow or fast) which innervates muscle fibers os most parts of the body
Strength of muscle contraction depends on the rate at which nerve impulses are transmitted to the fibers
Arthropods citculstory system
- open circulatory system with the oxygenated blood moving throguh a series of sinuses and finally being drawn back into the heart through ostia as the heart expands.
- dorsal artery carey oxygenated blood theough hemocoelic channels (unshaded vessels) for gaseous exchange between lungs abd tissues blood to the heart
- ventral artery collects deoxygenated blood (shaded vessels) to the gills to be oxygenated and retuned to the heart via the pericardial sinus
Arthropod respiration
Specialized structures
- fills in aquatic forms
- trachea or book lungs in terrestrial forms
Artrhopod ocelli
Simple eyes
- appear like a small cup with light sensitice surface covered by a lens
- it is supported by light absorbing pigments made up of vitamin A derivates suppeoted by a protein
- do not form images
- common in lower invertebrates
Arthropod compound eyes
- Image forming
- May be present alongside the ocelli
- made up of many individual units reffered to as Ommatidia
- gives a broad visual field
- compound eyes break down an image before it reaches the retina, thus, each ommatidia forms a small part of a single image
- common in bees, ants, cockraiches and crabs
Insects may be composed of many thousands of ommatidia which are oriented….
Each oriented in a slightly different direction from each other owing to the convex shape of the eye
5 parts of ommatidia
- Fixed-focus lens or cornea: focuses imsge far and near
- Underlying gelatinous Crytalline cone: serves as lens in some insects and majority if crustaceans
- Cylindrical cells/collars: contain shielding pigment; optically seperates each ommatidium from surrounding ommatidia
- Retinular cells: series of ~8 photoreceptors each containing light-sensitice pigment
- Neural cartridge: situated at the basal end, contains a cluster of neurons which recieves information from the retinular cells and send action potential to the optic ganglia for processing
Sexual reproduction in arthropods
(MOST COMMON)
- Internal fertilization: common in terrestrial species
- most are gonochoristic (seperate sexes)
- hermaphroditic occurs in few species mostly sedentary and parasitic ones
- development is usually indirect through larval stages
- parental care is often well marked in many arthropods
Arthropod asexual reproduction
Parthenogenesis: development of offspring from unfertilized eggs. Common among the class insecta, branchiopoda and some freshwater copepods; some of these members lack males
Mating partners in arthropods locate themselves via
Release of certain chemicals called pheromones
Spermatophores
Are specialized containers used by males of kany arthropods such as, insects, mites, copepods and scorpians, for indirect transfer of sperm to the female
Fertilized eggs of arthropods undergo varying stages of development which could be
Difect or indirect
95% of all arthopods are contained in a superclass…..
Crustacea and two other classes arachnida and insecta
Taxonomic classification of arthropods is mainly on differences in appendages which include:
- number of appendages
- distribution of appendages
- embryonic origin
- form and function of appendages
Subphylum Trilobitomorpha
- called 3 lobed arthopod
- possess two anterior-posterior furrows which divides the body into 3 regions (2 lateral, 1 central)
- no living species
- fossil evidence shows some walked, some burrowed and some swam
Triolibitomorpha body forms
- body generally flattened ventrodorsally and divided into 3 parts: cephalon, thorax and pygidium
- anterior and posterior sections are covered with unjointed sheet of exoskeleton known as carapace; covering the metamerization of these segments
- possess compound eyes made up of many ommatidia
- presence of metameric segments shows a primitive form of arthropods
Subphylum Chelicerata unique characteristics
- most possess claws
- no antennae or manibles
- lack distinct head
- body dividible into 2 portions (cephalothorax or prosoma and opisthosoma or posterior abdomen)
- furst pair of preoral appendages called chelicerae on the prosoma are modified for feeding
- first anteior segment lacks appendages
- second anterior segemnt possess a pair if appendages (chelicerae) adjacent to mouth for grabbing and shredding food
Superclass of subpylum chelicerata
And its two classes
Merostomata
Arachnida: spiders, mites, ticks
Pycnogonida: non segmented body
Superclass Merostomata unique characteristics
- appendages present on opitosoma are flat and adapted for gaseous exchange (book gills)
- terminal part of the opistosoma (posterior segment) possess a long pointed spike known as a telson
Merostomata possess how manu living species?
4, most are extinct
Horeshoe crab (Limulus polyphemus)
Members of the merostomata are all _____ and localized where?
Marine
Seas of eastern north america, indonesia and south east asia
Horeshoe crab use what part to aid in burrowing
Telson
Searching for mucro animals for feeding
Horsehoe crab burrowing helps to
Aerate the soil
Biotechnological application of the Horseshoe crab
- blood components used as bacterial screening tool: components of blood serve as a diagnostic tool for screening injectable pharmaceutical drugs for bacterial endotoxins
- also serves as a diagnostic component for detectinf diseases like meningitis, gonorrhea and others
- vision research: studies on eyes of horseshoe crabs provided insights for us
- important food source: larvae of horse shoe crab released on the sea surface are major food source for kigrateoy shore birds like red knots
Carapace
The head and thorax of merostomata are fused into a single functional unit, the prosoma or cephalothorax and are covered with a single, unjointed sheet of exoskeleton called a carapace
What is the only chelicerate with compound eyes
Hore shoe crab
Generic evidence reveals that the prosoma is similar to what
The hesd of other arthropods
How many appendages do Merostomata have?
6
All 6 pairs are found on the prosoma
First pair modified for feeding
Other 5 pairs are for walking (Pedipalp) and last pair has claws
Distinction of Pedipalp of male and female Merostomata
Males: use it for grasping feamle during mating
Female: same as other appendages
The first 4 pairs of walking appendages of merostomata are modified at base into ____
Toothed food grinding surface known as gnathobase
The fifth pair of appendages in merostomata are modified for
Digging mud burrows and cleaning the gills
Chilaria
Small, hairy appendages present at the last sefment of the prosoma; used for food crushing and transfer of food to the mouth
Opistosoma bears……
Also known as the abdomen bears 6 pairs of appendages; first for reproduction, other kodified as gills
Also bears gill flaps which contain numerous openings (150) book gills; function as surfaces for gas exchnage and channel for blood circulation
(Merostomata)
Class Arachnida
Habitat and examples
All 70000 described speicies are terrestrial; earlier memebrs were marine
Include spiders, ticks, scorpians
50% of arachnida are
9000 species are
Spiders
Mites and ticks
Spider feeding
Carnivorous; prey mainly on insects; maning then a good biocontrol agent
Class Arachnida body
Body divided into 2: Prosoma (fused head and thorax) and opistosoma
Prosoma bears carapace
Arachnida eyes
- spiders possess 0-4 pairs of simple eyes present on prosoma (4 most common)
- lack compound eyes
Arachnida appendages
6 pairs of appendages
- first pair=chelicerae for fedsing
- second pair=pedipalps for locomotion, defense and reproduction
- last 4 pairs for walking
Basal segment of pedipalp in arachnida contain
Maxilla for mechanical separation of food
The prosoms and opistisima of arachnia are connected by a stalk called
Pedicel thst allows for flexibility of the abdomen
Ticks and mites possess fused
Prosoma and opistosoma
Arachnida respiratory organs
- tracheae (small species)
- book lungs or book gills= flattened respirateoy surfaces in the abdomen, they are connected to the outside by means of openings called spiracles
-spiracles close after each breathe to acoud dehydration
Among small sized species of arachnids, spriacles may…
Lead into the tracheae (collection of tubules); thus gaseous exchnage not connected with circulatory system; trachea leads directly into body tissues
Spinnerets
Possessed by spiders, secrete silk proteins which serves several purposes
- scaffold for climbing
- escape danger
- webs for trapping prey
- egg sax that to protect embryo, making homes or mating
Class arachnida sexes and reproduction
Sexes separate (dioecious)
Mostly oviparous and courtship before mating. In some species, the make transfers sperm to the female in a spackage or spermatophore
-usually lay yolky eggs, which hatch into immature young that resemble adults
Arachnid diverse feeding styles
Omnivorous Carnivorous Herbivores Fungivores Parasites
Several mites and ticks are of medical and exonomic inportance as _____ and _____
Parasites
Agents of disease
- as ectoparasites, mites and ticks feed by sucking the host hody fluids with the aid of their muscular pharynx
- ticks transmit diseases such as rocky mountain spotted fever, lyme disease and encephalitis
- also include allergies and rashes on their host
Order acari
Habitat of arachnids
Freshwater, marine and terrestrial
Forest, moss, ant colonies, burrows, burd bests, decomposing vertebrate caraccases
Both young and old arachnids can be parasitic on _____
Lizards, burds and frogs
Economic impact of arachnids
Are agricultural pests directly or as vectors for plant viruses in begetables, fruits, flowers, tobacco and tea plants
Class Pycnogonida unique characterisitcs
- lack Tagmatization (body not distinctly segmented)
- unique proboscis at anterior end with opening at the tio
- variable number of walking legs
Pycnognids habitats
Strange habitats
- all marine species; commonly called sea spiders
- in oceans around world
Ancestor of most arthropods are
Pycnogonida
Body of Pycnogonida
Typically small body (few milimeters to 10 cm) with conspicuously long legs which are typically about 3x the length of the body and may be nearly 16x linger than the body.
- cephalothorax, abdomen (reduced to short stump)
- lack specialized repository or excretory systems unlike true spiders
Digestive system of Pycnogonida
Complete digestive system with a sucking mouth that opens at the tip of an often grestlt elongated proboscis
-digestive system continue to the legs; as do gonads
Appendages of Pycnogonida
6 pairs
- chelicera (feeding)
- pedipalp
- 4 walking legs
Ovigers
Pycnogonida head bears a pair of ovigers; used by both sexes go groom the legs and trunks; serve additinal role males to carey fertilized eggs
Pycnogonidia sexes
Dioecious (separate sexes)
- females have ovairws
- males have testes located dorsally in relation to the digestive tract
Pycnoginida reproduction
External fertilization
Posterior pair of ovigers (on head region) are used by males to carry the eggs after they are fertilized
Pycnoginids (juvenile) increase in size not only when they molt, but also____
During intermolt periods
Owing to its flexibke movement
Feeding of pycnogonids
Most adults are carbivores; feeding ok slower moving organsisms like sponges, bryozoans (moss animals) and colonial hydrozoans
Juvenile and some adults are parasitic or commensal in or on various marine invertebrates like gastropods, bivalaves, echinoderms and jellyfish
Ex: Pycnogonum, Nymphon
Young and adult stages of the Pyconogonum litorale can survive for ______ without feeding
Months
Subphylum Mandibulata unique characteristics
- possess jaws
- third segment appendages modified into mandibles for chewing
- possess antennae
- possess distinct head
Mandibulata appendages are
Uniramous or biramus
Mandibulata have separate _____ with _______
Sexes
Sexual dimorphism
Mandibulata may development involves either
Nymph or larval stages
Mandibulata includes 3 major groups
Myriapoda
Insecta
Crustacea
Habitat of Mandibulata
Terrestrial and aquatic (fresh or marine)
Body of Mandibulata is divided into
-two distinct portions (anterior cephalothorax or prosoma and posterior abdomen or opisthosoma)
Or
-3 distinct portions (head, thorax and abdomen)
Head appendages of Mandibulata consist of
- 1 or 2 pairs of antennae
- 1 pair of mandibles
- 1or 2 pairs of maxillae
Eyes of Mandibulata
Compound
Respiration of Mandibulata is
Either by gills or trachea
Excretory system of Mandibulata
Malpighian tubules or green glands
Superclass Myriapoda
- possess many foot (appendages)
- classified into 2 orders: Chilopoda and Diplopoda)
Order: Chilopoda
General body
Centipedes
- rounded or flattened head, bearing of antennae at the forward margin
- possess uniramous appendages (single branched)
- often lack eyes; when present, eyes generally are simple light receptors called ocelli.
- head is followed by 15 or more leg bearing segments. First pair of legs are called maxillipeds(for subduing prey)
- pair of elongated mandibles for chewing
- 2 pairs of Maxillae
- body covered with unwaxed cuticle
- reproductive opening on last body segment
Typically small (5-10cm)
Chilopoda habitat
Terrestrial and marine
Under soil, in humus, under logs and in homes
Respiration if Chilopoda
Via trachea
Chilopoda Spiracles
Spiracles open located on the sides or top of the body; thus, must inhabit moist environments to avoid dehydration
Or nocturnal adaptation
Male Chilopoda produce ______ that are usually picked up by females
Spermatophore
Chilopoda Head morphology
- possess 1 pair of antennae
- possess 1 pair of mandibles for chewing
- possess pair of 1st and 2nd maxillae
- possess simple eyes or lack
Trunk of Chilopoda
Bears 15 segments after the head; each having a pair of legs
- first pair of walking legs; modified into powerful fangs for killing prey (Maxillipeds)
- Repugnatorial glands on each segment of some species: release repulsive chemicals to ward of predators
Legs of Chilopoda are mainly for _____ but could serve for ____
Running
Burrowing
Order Diplopoda general body
Millipedes
- 2 pairs of legs on most body segments; attached to underside of body
- elongated cylindrical body, capable of rolling up
- head possess 1 pair of antennae, 1 pair of mandibles and 1 pair of maxillae
- cuticle harder than centipede due to calcium salt deposits like crabs
- most lack eyes: but some have up to 80 simple eyes: no compound
- 2 pairs of spiracles and ganglia on underside
- reproductive organ on 3rd body segment
Are Diplopoda fast?
No, not like centipedes
Diplopoda feeding
Primarily detritivores, some herbivores, few carnivores; no venom
Diplopoda reproduction
Make generally inserts spermatophore into female with Gonopods
Diplopoda head morphology
- single pair of uniramous antennae
- pair of mandible for chewing
- pair of maxillae
- no second maxillae
- first and second maxillae on each side are fused to form a single appendage (gnathochilarium)
- possess ~80 ocelli or lack
Diplopoda trunk/body morphology
- bears no segments after the head; each having 2 pairs of legs
- Repugnatorial glands are abundant on the segments of some species: release repulsive chemicals to ward off predators
- legs adapted for running or burrowing
Size of Diplopoda
Typically small, but some tropical species could be up to 30cm
Superclass Hexopoda unique characteristics
- loss of abdominal segments
- formation of lower lip (labium) by fusion of a pair of head appendages (2nd maxillae)
- 6 footed invertebrates
2 groups of Insecta
Insects
Entognatha
-primitive and wingless hexapoda which evolved independently of insects; but retain 6 legs
Class insects habitat
All habitats except deep sea
-terrestrial, aquatic and arboreal (trees)
Which class is most successful of all organisms
Insecta
Insecta body
- divided into 3 tagmata (head, thorax and abdomen)
- possess 3 pairs of legs; each on one of the 3 thoracic segments
- all appendages are uniramous
- compound eye on head
- 3 pairs of mouth parts for chewing, piercing, biting, sucking, siphoning
- pair of antennae
- 2 pairs of wings dorsal to thorax
Organ of hearing in Class Insecta
Tympanum organs
Insect respiration
- By trachea
- in groups where trachea are lacking, gas exchange is by diffusion across the cuticle
Insect excretory system
- excretion by Malpighian tubules, which are long, slender, blind-ending tubes
- primary end product of protein metabolism among insects is Uric acid. This nontoxic nitrogenous compound is excreted in nearly dry, solid form
Insect wings
- typically possess 2 pairs of wings dorsally on the thorax as outfolding
- Few species are wingless
- in flies, 2 hind wings are modified as halters for measuring angular velocity
- insects used to possess wings on abdomen segments but that has been lost
Insect reproduction
-mostly diecious
-females of some species require certain diet (mainly Protein rich) to fully develop their eggs
Ex: female mosquito require blood meal for nourishment during oogenesis prior to oviposition
-fertilization is internal, prior to oviposition
-oviposition can be done in water (mosquito), decaying matter (flies), attached to plants, inside other insects (predatory wasps)
insects possess several distinct developmental stages called ____
-instars
3 forms of insect development
- Hemimetabolous(half adult): young look similar to the adult; transition can be gradual in some species and the different instars are called nymphs (dragonfly, cockroach, grasshopper)
- Holometaboulus: Members undergo metamorphosis (series of gradual changes in the development of an insect embryo into adult. (Beetles, moths, butterflies, wasps, ants, bees, flies)
- Ametabolous: (primitive condition; no chance between young and adult) (bristletails)
Insect social behaviours
- some insects live social (communial life style) called Eusocial species. Ex: termite, bees, ants and wasps)
- members live in colonies with distinct morphological and physiological adaptations and roles
Ant social behaviour
- one Queen (gives rise to colony over many years using stored sperm from a single male, during mating season)
- sterile workers (mostly females, sisters)
- soldiers (mostly female)
- males are winged, produced by Queen periodically and delivers tally without fertilization (haploid) when needed to fertilize young queens which later develop to form new colonies; males killed after fertilizing the young Queen
Termite social behaviour
- possess Queen
- sterile and blind workers (male or female)
- soldiers
- secondary Queen and tertiary queen
Positives of insects
- important as plant pollinators
- food and food supplements
- important in food chain
- secrete medicinal products (honey and silk)
- biological control agent of other arthropod pests and vetors (parasitoids)
For parasitoids, female lays eggs into an adult host which develop into larvae to begin devouring the host inside out
Negatives of insects
- vectors of diseases that cost economically and medically
- pests of plants and animals (mosquito, caterpillar)
- parasites (ticks and mites)
Superclass Crustacea unique characteristics
- crust-like structure (carapace)
- head bears five pairs of appendages; 2 pairs of antennae
- nauplius: possess a larvae from with triangular shape having three pairs of appendages and a single median eye
6 major classes of Crustacea
Malacostraca Branchiopoda Ostracoda Copepoda Cirripedia Branchiura
Class malacostraca unique characteristics
- possess soft shells
- possess thorax with 6 segments, abdomen with 6-7 segments, with a telson
- appendages on the 6th abdominal segments are flattened to form a Uropod
Which class contains nearly 60% of all described crustacean species including decapods, euphausiids, stomatopods and amphipods?
Malocostraca
The body of class Malacostraca
- body is tripartite, consisting of a head, thorax and abdomen; head and thorax almost fused
- head and thorax are covered with a carapace; for which both can be regarded as a cephalothorax
- possess a rostrum: pointed spine above head
- body surface covered with chromatophores
Malacostraca head morphology
- large, stalked compound eyes
- 2 pairs of antennae for sensory function (1st pair called antennules, 2nd are antennae and may function in feeding, locomotion and mating)
- 3 smaller appendages that are involved in feeding or in generating respiratory currents
- mouth part include mandible (food crushing), and maxillae (generate water current and manipulate food)
Malacostraca Thorax
- bears 8 pairs of appendages: 3 maxillipeds (food manipulation), 5 pereopods (walking legs)
- first 3 pairs of pereopod may be modified into chelate (claws) and function in defence and feeding
Malacostraca abdomen
- six segments, each bearing a pair of appendages called pleopods (function in swimming, generating respiratory currents and aids females in egg brooding and nurturing the young.
- possess a terminal appendage called telson
Malacostraca appendage characteristics
- biramus (2 branches)
- protopodite: first branch point
- epipodite: lateral branches of the protopodite (function as gills or hill cleaners)
- endopodite: internal branch
- expopodite: external branch on appendages (less developed)
- chromatophores
- some members are secondarily uniramous as they lack exopodite and endopodite
Chromatophore function in class Malacostraca
For camouflage controlled by hormones; able to alter their colour based on the background environments
Class Malacostraca
Order Decapoda
- posses 10 thoracic appendages
- lobsters, crabs, shrimps, lobsters, hermit crabs
Class Malacostraca
Order Euphausiacea
Krill
- possess 8 pairs of walking legs at thorax
- no maxillipeds
- possess photopores: light producing organs distributed along the body; serve for mate recognition during reproduction, defence/camouflage and species identification
Krill impact
- krill biomass in the oceans surpass those of all aquatic organisms combined
- food for baleen whales, seals and sea birds
- some countries began krill exploitation for food
Class Malacostraca
Order Stomatopods
- shrimp-like, bottom dwellers
- up to 30cm
- mostly tropical
- fast moving
- live in burrows in rocks, mud and carpals of shallow water
- violent carnivores: 8 pairs of appendages on thorax; 2nd pair modified into large and powerful structure for smashing hard shell prey, spearing fish and other soft invertebrates
Class Malacostraca
Order Isopoda
- flattened dorsoventrally
- marine species, few freshwater and terrestrial
- lack carapace, have a pair of maxillipeds, antennae uniramous
- small sized (0.5-3cm)
-pill bug
Class Malacostraca
Order Amphipoda
- laterally flattened
- lack carapace
- mostly marine, few freshwater or terrestrial
Class Branchiopoda
- Named because they are gill-foot
- small, primarily Freshwater crustaceans
- free-living
- possess coxa gland (on each thoracic appendage), modified to form a large, flattened paddle; functions in gas exchange and locomotion
- appendages serve for respiration (gills), locomotion and filter feeding
Body of Branchiopoda is partially enclosed in a ______
Bivalved carapace
Some lack carapace like fairy shrimp
Fairy shrimp are restricted to mostly ______ environments
Harsh
Where predators are rare
Branchiopoda produce testing eggs that are resistant to extreme temperatures and desiccation called
Nauplius
Class Branchiopoda
Order Cladocera
- 1/2 of Branchiopoda
- include Daphnia, zooplankton
- bivalved Carapace
- microscopic
- head, with large biramous second antennae to propel through water
- thoracic region bears 5-6 pairs of appendages to generate feeding and respiratory currents with satae
- lack abdominal appendages
- compound eye; not stalked, but can rotate
- Cyclomorphosis
Cyclomorphosis
Seasonal alternation in appearance/ morphology; adaptation to evading predation in Cladocera
Class Ostracoda unique characteristics
- head and body are covered with bivalved carapace
- trunk of body contains a maximum of 2 lies of limbs
- small crustaceans in all water and some land
- head makes up most of body
- 2 pairs of appendages
- lack external segmentation
- large antennules and antennae for swimming
- mandibles are equipped with palps
What are class Ostracoda called
Minute mussel or seed shrimps
Lifestyle of Class Ostracoda
- most free living, some commensal
- may be carnivores, suspension feeders, scavengers and herbivores
Class Copepoda body characteristics
- thorax and abdomen bears 5-6 segments
- first thoracic segment is fused with head
- lack abdominal appendages
- most bear single nauplier eye (3 lens with ocelli), some have 2 eyes some none
- small sized zooplankton
- carapace
Habitat of class Copepoda
- most marine, some freshwater, few terrestrial in soil or moist surface
- bottom dwelling species live attached to substrates forming meiobenthos (sediment dwelling)
Feeding of class Copepoda
-feed on unicellular, free floating, photosynthesizing protists called phytoplankton in lakes and ponds
How do Copepoda collect phytoplankton
Through activities of the 1st and 2nd maxillae
Locomotion of planktonic Copepods accomplished by
Actions of a pair of biramous second antennae
Benthic species of Copepodes use what to move
Those acid appendages to walk over surfaces
Copepods lack _____ and _____
Gills
Abdominal appendages
Male Copepoda use _______ to capture females for mating
One or both first antennae
Also one or both of the males first thoracic appendages may terminate in a claw which is used to hold the female during mating
Female Copepoda carry eggs in a
Egg sac
Larval stage of Copepoda
Nauplius
Parasitic Copepoda
-most free-living, 25% are parasitic on different species of vertebrates and invertebrates
Class Pentastomida characteristics
- body possess 2 pairs of appendages with claws
- all are internal parasites of vertebrates even their larval stages
- body is worm like, having their body segmented and covered in a chitinous cuticle
- digestive tract simple and tubular
- no circulatory, respiratory or excretory organs
- adults are legless; larval stages possess 3 pairs of appendages
- larval Legs are jointed
Adult Pentastomids dwell mainly in _____
Lungs and nasal passages of reptiles, amphibians, birds and some mammals like dogs and horses
Pentastomid are ____________ endoparasites
Blood sucking
Cloning to host tissues with sharp anterior hooks
Pentastomids are ______ and undergo ________ fertilization. Embryogenesis occurs within a _____
Gonochoric (separate sexes)
Internal
Shelled capsule
Pentastomid Nascent, encrusted parasite usually leaves the host in _______
Nasal secretions and saliva
Development of Pentastomida is halted until
Once consumed….
Eaten by a suitable intermediate host(vertebrate); insects may act as obligate intermediate host for some
Larvae emerge, tear through the gut wall and develop further within species-specific tissues, then undergo up to 9 moles before reaching a stage infective to final host
A definite host of Pentastomida becomes infected by
Consuming an intermediate host containing the Pentastomid larvae; juvenile parasite emerge, move to the pharynx, then respiratory system with its claws
Direct infection(without intermediate host) of Pentastomid
Observed in Norwegian reindeer; where young larvae can invade the placenta tissue of a pregnant female to infect the fetus
Class Cirripedia characteristics
- thoracic limbs modified as filtering cirri
- lack abdomen
- poorly developed body segmentation
- lack compound eye and antennae as adults
- Carapace forms a pair of folds of mantle Surrounding the body and covered externally by calcareous plates
Members of class Cirripedia are commonly known as
Barnacles
Habitat of Cirripedia
- attachment to substrates or as parasite
- exclusively marine and sedentary; permanently affixed to or burrowed into living or non living substrate
- free living but also parasites sometimes
Barnacles lack
Abdominal segments
Gills and a heart
Blood circulated entirely by movement of the body
Feeding in Cirripedia
- alternates between active and passive feeding since they live attached depending on velocity of the water current
- slow water current results in active feeding; actively creates current and collects food materials from surrounding water
- fast moving water results in passive feeding: food materials are sieved from flowing water passing through the cirri
General and common larval stage in crustacea are _____ and are common among
Nauplius
Isopods, Cirripedes, ostracods, Branchiopods, euphausiids
Periodically can only in other intermediate larvae forms depending on species before reaching adult
In Copepoda, the nauplius gives rise to _______ which undergoes ____ stages to become adult
Copepodite
5
In barnacles, the nauplius gives rise to ________ and active feeder which gives rise to adult
Cypris larva/Cyprid
Decapods like crabs and shrimps do not pass through ______ stage, but instead
Nauplius
Brood their young externally, beneath the abdomen to a more advanced stage called Zoea larvae, with a characteristic compound eye and spiny carapace
Zoea larva undergo several changes and metamorphosed into _______ which gives rise to
Megalopda larvae
Adult decapod
