In this work, a tritrophic food chain model has been proposed by incorporating Ivlev-like nonmonotonic functional response, where prey is equipped with defense ability. We have performed a detailed dynamical study and pattern formation analysis to obtain complex dynamics of the proposed system. Stability and bifurcation analysis have been performed in the model system. Persistence and permanence are discussed. Bifurcations of codimension-1, in particular, saddle-node, transcritical and Hopf bifurcation are observed. The model system also exhibits bifurcations of codimension-2 such as cusp, Bogdanov-Takens and generalized Hopf bifurcation. Interestingly, it is observed that the middle and top predator population become extinct due to defense ability of prey. Chaotic dynamics is observed via a period-doubling route to chaos with the change in the value of parameter $\beta$. The quantification of chaotic dynamics is done, using Lyapunov spectrum and sensitivity analysis. Diffusion induced chaos is studied in the spatiotemporal model system. Hopf bifurcation is seen in the case of a spatially extended system. Further, conditions for Turing instability have been obtained. Pattern formation study is done. In the two-dimensional spatial domain, various non-Turing patterns such as hot-spot, cold-spot, labyrinth patterns are obtained. Ripple and stripe Turing patterns are obtained in case of one-dimensional spatial domain. Also, labyrinth and patchy Turing patterns are obtained in the two-dimensional spatial domain. The spatial distribution of the species shows Turing patterns at the low cost of $\beta ,$ while the increased cost of $\beta$ changes Turing patterns to non-Turing patterns. Throughout the study, we observe that the parameter $\beta$ plays an important role in group defense mechanism and is the most sensitive parameter leading to vital change in system dynamics. A wide range of Turing and non-Turing patterns obtained in this work has not been reported so far in literature in any model with group defense.

在这项工作中，已经提出了一种三养性食物链模型，该模型通过结合像Ivlev一样的非单调功能性反应来实现，其中猎物具有防御能力。我们已经进行了详细的动力学研究和模式形成分析，以获取所提出系统的复杂动力学。在模型系统中已经进行了稳定性和分叉分析。持久性和持久性进行了讨论。观察到codimension-1的分叉，特别是鞍形节点，跨临界和Hopf分叉。该模型系统还显示了codimension-2的分支，例如尖点，Bogdanov-Takens和广义Hopf分支。有趣的是，由于捕食者的防御能力，中，高级捕食者种群已灭绝。$\beta$。使用李雅普诺夫频谱和灵敏度分析完成了混沌动力学的量化。在时空模型系统中研究了扩散引起的混沌。在空间扩展系统的情况下，可以看到霍普夫分叉。此外，已经获得了图灵不稳定性的条件。模式形成研究已经完成。在二维空间域中，获得了各种非图灵模式，例如热点，冷点，迷宫模式。在一维空间域的情况下获得波纹和条纹图灵图案。另外，在二维空间域中获得迷宫式和斑驳的图灵图案。物种的空间分布显示了图灵模式的低成本。$\beta ，$ 而增加的成本 $\beta$将图灵模式更改为非图灵模式。在整个研究过程中，我们观察到$\beta$在群体防御机制中起着重要作用，并且是导致系统动力学发生重大变化的最敏感参数。迄今为止，在任何具有集体防御的模型中，迄今尚未在这项工作中获得各种各样的图灵和非图灵模式。