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Crustaceans Body Only Was ~2’ Long, Claw Was an Additional 20” Crustaceans body only was ~2’ long, claw was an additional 20” =shelled creatures; “the insects of the sea” ! ~ 4’ long total some crustaceans are quite colorful; blue, red, ~67,000 species orange, yellow eg: lobsters, crayfish, shrimp, crabs, water fleas, many are bioluminescent copepods, barnacles, pill bugs, etc A. crustaceans are mostly aquatic, the great majority vary in size from microscopic (<0.1 mm) to 12’ are marine some crustaceans live for several decades; some inhabit most waters of the earth: ocean , arctic , freshwaters, molt throughout life high mountain creeks and lakes thermal springs, brine waters so continuous increase in size 1. many are benthic eg. crayfish & freshwater shrimp eg. especially the larger crustaceans; shrimp and crabs largest crustaceans in freshwaters eg. also isopods, amphipods some up to 2’ and weigh 9 lbs e. Ostracoda (=seed shrimp) a river shrimp, Macrobrachium jamaicense, was collected from Devils River, Tx: body was 10.5” common in freshwater and marine habitats long, 3’ long including antennae, 3 lbs mainly benthic animals that inhabit all types of eg largest (longest) is giant Japanese crab substrates in standing and running water ! up to 12’ from end of claws to tail and a weight of a few actively swim just above the substrate 40 lbs (20 kg) generally use their antennae to move Lobsters may be the longest lived Crustaceans enclosed in bivalve carapace that completely covers one was collected that weighed 35 lbs the entire animal was estimated to be 50 yrs old; Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 1 Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 2 their shells are so strong that they fossilize well found most abundantly in oceans but also common in freshwaters important to paleontolotists in dating sediment may be the most abundant animals on the planet (65,000 fossil species vs 13,000 living species) feed in a variety of ways: scraping food from hard generally feed on bacteria, fungi, algae and detritus surfaces, filtering articles from the water, seizing and biting prey viable eggs have been collected from dried ponds and revived after 20 years extremely important food source for marine fish some crustaceans construct tubes in sediment, majority of the diet of commercial fish is copepods wood and rock some are important vectors for diseases such as eg. boring isopods can destroy wooden pilings in less guinea worm than 2 yrs eg. Water Fleas (=Cladocerans) some isopods can tunnel through limestone rock cladocera are most abundant in permanent some have been known to burrow through the freshwater ponds & lakes, among marginal insulation of undersea cables shorting them vegetation out ! important part of freshwater zooplankton some crustaceans are sessile (=attached) body is enclosed within a bivalve shell called a eg. barnacles common in intertidal areas carapace that covers the thorax and the abdomen but not the head 2. many small are at the base of aquatic food large eyes – looks like a single eye but is actually 2 chains part of zooplankton compound eyes that are fused together eg. Copepods very large antennae that are used for locomotion small, slender, clearly segmented body inside the carapace are 5 or 6 pairs of feet used to filter the water for food large pair of antennae used for movement female carries her eggs around in a brood pouch feathery legs to filter food enclosed in carapace eggs hatch and young swim free – direct development Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 3 Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 4 only animals that flourish in the Great Salt Lake of eg. Krill (Euphasids) Utah and other hypersaline environments small shrimp-like animals extremely abundant in their eggs can persist in dry salty lakebeds marine plankton today they are cultured extensively as fish food or as 3 often occur in swarms up to 30,000 individuals/m novelties; “sea monkeys” a major part of the diet of whales, seals, penguins and C. while the vast majority of crustaceans are aquatic, cephalopods among others some groups are semiaquatic or terrestrial eg. whales eat 2-3 tons of krill per meal eg. land crabs burrow above tide line into the water table eg. freshwater zooplankton: can survive days out of water esp. water fleas, copepods, seed shrimp eg. pill bugs & sow bugs (isopods) B. certain specialized crustaceans are the dominant isopods are the only group of crustaceans with truly animals in highly saline or alkaline environments terrestrial representatives or in temporary waters such as playas have very delicate gill-like respiratory organs that eg. fairy shrimp, tadpole shrimp, clam shrimp must be kept moist generally inhabit temporary pools, ponds and playas found in damp places under stones and logs and are generally completely absent from able to roll up for protection (=rolly pollys) permanent bodies of water young develop in brood pouch feed mainly on algae, bacteria, protists and microscopic animals some salt water relatives are found along coasts and live in seaweed, along rocks and algae typically appear in the spring and disappear in late summer or autumn as habitat dries some bore into wood causing destruction of pilings and warves to survive most produce very drought resistant eggs that can survive dried or frozen for years in eg. beach fleas or sand hoppers (amphipods) lake beds some are almost terrestrial; found crawling around on eg brine shrimp (Artemia) piers and jetties Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 5 Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 6 Crustacean Body Form most appendages are biramous the most ancient crustaceans resembled some kind of aquatic centipede; lots of segments, each with a they branch like a “wishbone”; one of the pair of appendages branches usually has a gill attached at its base only one small group of these kinds of crustaceans remain today most primitive species had long segmented body with similar segments and similar appendages in most crustaceans today, the body is usually divided into a cephalothorax, abdomen and tail over time, great variety of body types arose cephalothorax appendages modified for a variety of uses: sensory often have carapace extending over the sides of feeding defense the animal walking swimming in some groups carapace forms clamshell like valves that reproduction encloses the whole body respiration in others the carapace covers cephalothorax but not abdomen lots of variation in appendages between groups abdomen eg in decapods (crayfish, crabs, lobsters, etc): 1st 2 pair ! antennae with chemoreceptors segmentation is most apparent in the abdomen next 5 pr (3-8) ! feeding appendages; including mandible, maxilla and maxillipeds abdomen usually with pairs of jointed appendages on most segments next 5 (9-13) ! walking legs including cheliped and gills Movement next 5 (14-18) ! called swimmerets; used to carry eggs and as copulatory organ generally have many pairs of appendages Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 7 Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 8 last (19) ! uropod = swim fin live in solitary burrows eyes are stalked and constantly watch for prey most crustaceans can cast off legs or pinchers and regrow them some are suspension feeders voluntary (striated) muscle tissue arranged in eg. barnacles sit upside down in shell and use legs to strain water for food antagonistic groups eg. flexors & extensors some are scavengers similar to vertebrates eg. isopods, amphipods Feeding & Digestion crustaceans have a well developed digestive system: cardiac stomach with gastric mill for grinding use jaw-like mandibles as main feeding structures gastric mill has hardened “teeth” also maxillae and maxillipeds pyloric stomach for sorting great variation in feeding types: digestive gland secretes digestive enzymes many are predators Respiration eg. crabs use large claws used to break open shells to feed in small crustacea: no special organs eg. mantis shrimp is an ambush predator, extremely carnivorous and ! exchange across body surface aggressive in larger crustacea: respiration usually by feathery called “split thumb” in Bermuda and West Indies gills front end looks like praying mantis on bases of walking legs has “jackknife claws” Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 9 Animals: Arthropoda - Crustacea; Ziser Lecture Notes, , 2012.10 10 in some sides of carapace form gill chambers at base of antennae that enclose gills saclike; opens to surface by pore have an appendage called a “bailer” that creates a water current across gills take in sand grains which trigger hair cells to provide info on orientation Circulation 6. hearing: communication by sound open circulatory system many crustaceans make underwater noises to most crustaceans have some kind of blood pigment to communicate better distribute oxygen to tissues eg. pistol crabs snap claws together producing sound most: hemocyanin ! bluish pigment with Copper like pulling a cork from a bottle others: hemoglobin ! red pigment with Iron eg. one species of mantis shrimp makes a vigorous rasping noise by rubbing uropods against some: no pigments underside of telson eg. Florida spiny crab produces sound like moist Sense Organs fingers rubbing against a window pane sense organs are well developed in crustaceans some crabs have striae or ridges on inner side of chelae that they rub against tubercles on 1. most have compound eyes and simple eyes carapace
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